Caster's True Name is Zhuge Kongming (諸葛孔明, Shokatsu Kōmei?, Kongming is his Courtesy name, Zhuge Liang) was a prominent politician in China's Three Kingdoms era. He was widely known as a military strategist, it was reported that it was mainly due to his abilities that the weaker and smaller state of Shu was able to resist the much larger Wei army for a quite some time. In death, Kongming still out smarted Zhongda.(
Due to the "extremely peculiar circumstances" of the Grand Orders, Lord El-Melloi II was forced to become a receptacle for his spirit to facilitate a successful summoning. Lord El-Melloi II himself lacks the means or history to become a Heroic Spirit. In the process, the Master Strategist analyzed who would be best in charge. Kongming judged that there was no need for himself to come to the forefront, since he already had a competent agent, so the role fell to Lord El-Melloi II, who was already acquainted with the modern era.
Caster takes the appearance of Lord El-Melloi II but as his ascension progress increases, his appearance takes the form of Waver Velvet.
Kongming is described as a monster of rationalism. The rationalism of Chinese and Western philosophies is incompatible. His thoughts and feelings are more in accordance with Lord El-Melloi II. Lord El-Melloi II only spoke with Kongming for a few minutes, but he calls Kongming a monster from ancient history and it didn't feel like he was talking to a human.
Lord El-Melloi II's dream was to reach Okeanos, but explains he is not quite ready to go find the boundless sea.
Second Singularity: Septem
El-Melloi II appears in the Singularity after becoming the vessel for Zhuge Liang. He serves as Alexander‘s strategist against Nero Claudius‘ army. After reporting on Nero’s army, he suggests luring Spartacus and Lu Bu instead of taking them on head-on. He decides to fulfill Alexander’s wish to see Nero to the latter’s embarrassment. He then becomes annoyed that he became the vessel for a Heroic Spirit he has no connection to. He wonders what happened to his era and if he switched with Zhuge Liang. He also wonders if time stopped in his era and he’s now in the era fused with Zhuge Liang. When Darius III attacks the vanguard of Nero’s army, El-Melloi II wonders if Lev Lainur Flauros summoned him. He quickly realizes though that it was Alexander, who admits he wanted to try a chained summoning after hearing Elizabeth Báthory and Tamamo Cat were summoned the same way with Stheno. El-Melloi II is disappointed he would rely on such luck in battle. He also deduces Darius’ identity since he materialized through a chained summoning with Alexander. Then, while Nero’s vanguard is busy with Darius, El-Melloi II and Alexander hit her rearguard with a pincer attack. Though most of their troops are killed, they manage to lure Spartacus and Lu Bu away and captured Boudica. She is brought to a fortress near the United Roman Empire’s capital. El-Melloi II puts her under a restraint spell that ends up putting her to sleep.
When Ritsuka's party arrives at the fort, El-Melloi and Alexander introduce themselves. El-Mello II says it’s fine to forget his name though since he isn’t a true Heroic Spirit. He reveals he is a Stray Servant and gets annoyed by Alexander thanking him for fulfilling his wish to see Nero since he was merely following his direction. After the group defeats him and Alexander, El-Melloi finds it just like Alexander to meddle with others’ lives and disappears.
Fate/Accel Zero Order
When a Singularity manifests in the same coordinates as Singularity F at the time axis of ten years ago, Romani Archaman has El-Melloi II brought in to explain since he’s familiar with Fuyuki. As his knowledge differs from Chaldea's records, El-Melloi II explains the Holy Grail War occurred five times in his world while only once in Chaldea's in 2004. Romani is shocked by the number, to which El-Melloi II explains the Mage’s Association and Holy Church colluded to keep it secret in his. He then reveals the Singularity's time axis matches that of the 4th Grail War, finding it unsurprising Chaldea would detect a Grail there. He notes it should be impossible to observe the light of civilization in the past on a normal temporal axis since human history was incinerated. He recognizes though the Singularity is still a stain on human history that will eventually contaminate it. He then reveals the Grail War repeated five times in Fuyuki because the Grail never manifested itself. He also warns against retrieving the Grail, revealing it wasn’t a wish granter like the participants thought, but a weapon meant to destroy the world. He also says he put in considerable time in dismantling the Grail for this particular instance. He, Ritsuka, and Mash then rayshift to the Singularity.
Arriving in the Singularity, El-Melloi II uses Unreturning Formation to unveil Hassan of the Hundred Faces, knowing of her ability to split into multiple entities to survey Fuyuki. He knew the rayshift would draw attention, and Hundred Faces would come to investigate. He then has Ritsuka and Mash defeat her while she’s still trapped, promising to explain everything later. Afterward, he warns the pair that she’ll keep sending copies of herself after them. He then says that since they're on a tight schedule, he'll only explain the vital parts for now.
At the wharf, El-Melloi II reveals Angra Mainyu will activate and destroy the world once the required number of Servants are sacrificed to the Grail. He calls Singularity F the likely conclusion of the 5th Grail War. Mash asks him why such a ritual would be made, to which he responds it had a different purpose before a certain man-made disaster. He calls the situation a paradox, as Fuyuki should be in flames if the Grail already manifested like SHEBA detected. He, therefore, deduces Chaldea detected a different Grail. He then explains tonight is where everything begins, so they need to stay ahead of events, which the wharf is the key to. Irisviel von Einzbern and Artoria Pendragon then arrive, having come to the wharf at Diarmuid Ua Duibhne‘s, who isn’t present, invitation. El-Melloi II reveals Artoria’s True Name and tells Irisviel they will be their opponents instead of Diarmuid. He tells Ritsuka and Mash to force Artoria to retreat.
After she retreats, Diarmuid (previously kept at bay by the Stone Sentinel Maze) arrives. El-Melloi II asks him to stay calm while revealing his True Name, and explains they’re not Kayneth El-Melloi Archibald‘s enemies. He tells Kayneth that they came to support him. He gives Reines El-Melloi Archisorte as his guarantor since he can’t divulge his name now. Kayneth is convinced to leave the group alone when El-Melloi II says he’ll reveal more and Gilles de Rais’s current location.
After leaving the wharf, El-Melloi II explains again what will happen if the Grail is completed. Thus, he concludes the war was never meant to have a winner. He imagines he would turn evil from despair if he won the 5th Grail War. He then reveals his plan to prevent the Grail's activation by convincing at least three Servants to withdraw. The group can then use that opportunity to remove the Grail’s vessel. El-Melloi II warns not everyone will agree with their plan, so they need to eliminate any disagreeable Servants such as Gilles and Gilgamesh. He then reveals Hundred Faces’s Master is colluding with Gilgamesh’s, so it’s inevitable that they’ll fight her again. Everything regarding Lancelot depends on his Master, Kariya Matou, since direct reasoning is impossible. It is also crucial they convince Kariya while Lancelot is still under his control without using Command Spells. El-Melloi II warns Lancelot may go on rampage independent from Kariya’s will. He agrees with Mash that they should postpone meeting Kariya for now despite the risk. He then concludes their best chances for success lie with Artoria, Diarmuid, and Iskandar. He becomes momentarily somber when asked if Iskandar’s team will cooperate, and replies that it’s possible.
When Mash fails to connect with the leyline to establish a summoning circle, El-Melloi II deduces it’s because the Tohsaka controls the leylines. He decides they need to destroy the keystones set by Tokiomi Tohsaka so they can take control of the leylines. Romani warns Tokiomi will be angered if they do that. El-Melloi II replies the Tohsaka are already enemies for summoning Gilgamesh. He learned of the keystones' locations while working with the Tohaska heir and his former student, Rin Tohsaka, to dismantle the Greater Grail. He knows taking the leylines will impoverish the Tohsaka, but feels it’s their fault as one of the clans responsible for the Grail War.
While destroying the keystones, the group encounter Gilles’ monsters in an alley. After slaying them and securing the leyline point, they go to meet with Kayneth. Along the way, El-Melloi II requests Ritsuka to allow him to handle negotiations. He’ll keep a secret telepathic channel open and warns them to keep quiet.
In his suite, Kayneth states he learned from the Archisorte that El-Melloi II was lying about working on Reines’ behalf. He agreed to meet, though due to El-Mello II knowing about the Church’s actions toward Gilles beforehand. El-Melloi II then reveals information that should be privy only to the war's participants and Kayneth himself. He also wasn't lying about working for Reines, but he wouldn’t officially receive that duty until four years later. Therefore, everything he just said are memories of his past. When Kayneth asks how such a thing is possible, El-Melloi II explains it is Chaldea’s technology. He then lies to Kayneth that the Archibalds were responsible for such achievements through his leadership. Kayneth believes all this and agrees to help kill Gilles to earn a fourth Command Spell from Risei. The group then heads for Gilles's hideout in the sewers.
There El-Melloi II explains to Kayneth that they must be careful about discussing things not observed by anyone on the current temporal axis. Otherwise, the ripples from the changes in history will grow strong enough to possibly activate the Counter Force. El-Melloi II further adds that their intervention has made the future uncertain.
Eventually, the group confronts Gilles in his workshop and kills him. Afterward, they agree to kill his Master, Ryuunosuke Uryuu, since he's a dangerous murderer as stated by El-Melloi II. Kaynetth leaves with Diarmuid for the church to retrieve his prize.
However, the group finds Uryuu already dead when El-Melloi II uses Unreturning Formation to unveil EMIYA. El-Melloi II deduces he isn't a Servant of the 4th Grail and he's connected to what turned it into a Singularity. The group then fights EMIYA hoping to capture him for interrogation. Unfortunately, EMIYA escapes when the fight is interrupted by Waver and Iskandar. El-Melloi II reprimands Waver for thinking he’d arrive first, calling his method of finding Gilles’ workshop primitive. He further says that Waver ends up overestimating his own strength because he always gets out of trouble thanks to pure luck, which is precisely why he will never improve. Waver questions if El-Melloi II is either Caster or his Master, which frustrates El-Melloi II for him not fully analyzing the situation. Waver assumes he’s the Caster that Riese spoke of through reading his status. El-Melloi II counters though that if he can read his status, he should be able to tell he’s a Pseudo-Servant to Waver’s confusion. Iskandar discerns that El-Melloi II and the others are a third party unrelated to Caster, much to the latter’s relief. He assumes El-Melloi II was trying to pick a fight with Waver, though that wasn’t the case. After retreating to avoid fighting Iskandar, El-Melloi II gets frustrated at him while telling the others to ignore him and Waver.
After Mash finishes establishing a summoning circle, Artoria arrives and challenges the group to a fair fight. El-Melloi II is doubtful though, as he knows she is merely a decoy used by Kiritsugu Emiya to strike. The group then fights Artoria, hoping to force her into retreating again. As they fight though, Mash protects Irisviel from a sudden ambush by EMIYA. Artoria fights him, so the group supports her to not lose her.
After EMIYA retreats, El-Melloi II convinces Irisviel that they’re not enemies; something Artoria should have realized from their first encounter. He asks Irisviel if she knows EMIYA, but she doesn’t. He calls his presence an irregularity, so their immediate goal is to discover his identity. Irisviel feels like she was meant to be killed by EMIYA, but Artoria refuses to believe so. El-Melloi says the intuition of an Einzbern homunculus cannot be easily dismissed though.
Making peace with Irisviel and Artoria, the group head for Kayneth’s suite. Along the way, Romani asks El-Melloi what they’re going to do about Kaynet since he's still enemies with Artoria. Recognizing the limitations of being friendly with both sides, El-Melloi II concludes further inflating Kayneth's ego is the best way to convince him. He then unveils Hundred Faces, who's been stalking the group, with Unreturning Formation. The group defeat her and move on to meet with Kayneth.
At his suite, Kayneth informs El-Melloi II that he sent a familiar to the Matou mansion like he suggested and negotiated with Kariya. Kariya agreed to join under the condition they provide an opportunity to fight Gilgamesh. Thanking Kayneth for the information, El-Melloi II convinces him that the Grail War is a false one set up by his family's enemies, the Trambelios, in collusion with the Tohsakas to lure him away from the Clock Tower so they can increase their influence over the Association. Intervening with the conspiracy is why Ritsuka's party came to the past, but they couldn't warn Kayneth until they observed evidence in the past that a conspiracy existed. El-Melloi II tells Kayneth to hurry to London to stop the Trambelios’ plot. Diarmuid is ready to accompany his Master, but Kayneth orders him with a Command Spell to stay and continue the Grail War for his family’s reputation. He then lends Diarmuid to the group for that purpose. He asks El-Melloi II about the love letter draft he left in his study, though he’d never let anyone in his study while something so embarrassing is still there. He assumes the study that El-Melloi II is referring to is one whose master never returned to. El-Melloi II confirms such and feels honored by Kayneth’s thanks. He calls him the lord he wished to be and his talents as the greatest treasure in the Clock Tower.
After the group leaves the hotel, Romani reminds El-Melloi II that it’s impossible to change the past via a Rayshift. El-Melloi II recognizes his actions are meaningless, but he refuses to repeat the same mistakes twice.
Meeting with Kariya later, El-Melloi II informs him that Gilgamesh is discussing kingship with Artoria and Iskandar. The group interrupts the discussion and defeats Gilgamesh with Kariya and Lancelot’s help. Unfortunately, Lancelot attacks Artoria when Kariya collapses from expending too much magical energy. El-Melloi II tells the others they need to eliminate Lancelot, as they can’t lose Artoria and Lancelot served his purpose done with Gilgamesh gone. However, Iskandar stops the finishing blow and joins Lancelot against El-Melloi II. El-Melloi II asks him why, as he did everything to avoid this conflict. Iskandar replies it’s because he doesn’t like him to El-Melloi II’s devastation and for interfering with in the Grail War. Diarmuid considers defeating Iskandar on Ritsuka’s order, but El-Melloi II reminds them they’re only allowed to defeat four Servants.
After Waver and Iskandar leave with Kariya and Lancelot, EMIYA arrives to try to kill Irisviel again. El-Melloi II recognizes they’re both after the Lesser Grail, but their methodologies differ. He then explains what Irisviel's purpose and role were during the 4th Grail War he remembers. Artoria however reveals Irisviel is her Master, with Irisviel showing her Command Spells to reinforce this point. The group then fights EMIYA, but El-Melloi II stops it to talk. He reveals EMIYA is a Counter Guardian sent to prevent the activation of Angra Mainyu. Confessing he, Ritsuka, and Mash are from a different timeline, El-Melloi reveals the risk of the Einzberns winning had caused the Counter Force to intervene. He confirms the Singularity is an alternate timeline where the Einzbern dominated the 4th Grail War and surmises Irisviel is the Grail Chaldea detected. He then gives EMIYA the opportunity to solve the situation without killing Irisviel, which EMIYA accepts.
In the Grail’s cavern, the group prepares to destroy the Greater Grail directly since their previous plan has been compromised. El-Melloi II and EMIYA detect Hundred Faces trying to ambush them, and the group defeats her utterly. EMIYA guesses her Master didn’t understand how to utilize her abilities. El-Melloi II deduces Tokiomi may have switched to her after losing Gilgamesh. The group then moves on to the Grail’s chamber.
There El-Melloi II explains Angra Mainyu won’t activate with three Servants defeated. Even if it does overflow, it’ll only be a mass of ambiguous curses without purpose, something the group can handle. Iskandar then arrives. El-Melloi II asks him if he intends to continue the war, even though he should be able to sense the cursed magical energy emanating from the Grail. Iskandar doesn’t care because he merely wants to entertain himself and El-Melloi II. El-Melloi II is frustrated he would fight for such a selfish reason when the world is facing a crisis. He then fights Iskandar after the latter accepts him as a worthy opponent. 
He defeats Iskandar, though he believes he couldn’t have done it without Zhuge Liang’s power since his own power is lacking. Iskandar however tells him it only matters how said power is used. El-Melloi II cries when Iskandar disappears because he never expected to meet him again like this. Unfortunately, he is ambushed by Lancelot, whose now Zouken Matou’s Servant, and rendered unconscious.
Outside the chamber, he regains consciousness. His Spiritual Core is undamaged, but his body isn’t moving. Ritsuka informs him that Artoria and Diarmuid are currently holding off Black Iri (who Zouken summoned after Lancelot was defeated). El-Melloi II says they need to fight, but Waver points out he's too weak to do so. El-Melloi II tells Waver that he’s the key to victory, knowing full well of his inferiority complex. He then transfers Zhuge Liang's powers to Waver by instructing him to take his hand and pray “The art of certain victory, the mode of harmonizing with charges, is a matter of opportunity.” Waver becomes Zhuge Liang's temporary vessel and goes with Ritsuka and Mash to help Artoria and Diarmuid fight Black Iri.
After Artoria and Diarmuid disappear with the Grail’s destruction, Irisviel accepts Mash's invitation to return with them to Chaldea. El-Melloi II tells Waver that Zhuge Liang will return with them, so Waver will return to being a regular human. He further tells him to study and become stronger while he can, as he will come to wield this power someday. Waver compares El-Melloi II to Iskandar, though El-Melloi II believes he can’t match Iskandar yet. Waver asks him if he's trying to become Iskandar's equal. El-Melloi II ignores the question and returns Waver to the surface. Afterward, he returns to Chaldea with Ritsuka and Mash and is placed into the ICU.
Lady Reines Case Files
When a Singularity manifested at the end of the 19th century London, Ritsuka and El-Mello II rayshift there. However, they’re separated and lose contact with Chaldea. El-Melloi II sensed something was amiss with the Singularity and investigated the matter. He eventually discovered Mnemosyne was planning to alter Ritsuka’s memories through the paper scraps created by her. This however attracts Mnemosyne’s attention, forcing him to separate Zhuge Liang’s Spirit Core from his body to create a dead copy of himself at his apartment. While the action left him with nearly none of Zhuge Liang’s powers, it enabled him to continue investigating without being detected as a Servant. He also activated Chu Shi Biao, which caused Reines and Luviagelita Edelfelt to be summoned into the Singularity as Pseudo-Servants fused with Sima Yi and Astraea along with Gray, who was summoned as a regular Servant. He then left a dying message comprising only of the letter M, knowing someone would eventually find and discover its meaning. During his investigation, he removed some paper scraps from Charles Babbage‘s Difference Engine in his castle in the Patchwork of Dazzling Steam. He discovered the paper scraps were placed at specific locations for Ritsuka to find; the first two containing their original memories while the final would fabricate them. He also discovered the Singularity is consuming Ritsuka’s memories to extend its lifespan.
Upon discovering the final scrap was a trap, El-Melloi II rushed to the Patchwork Fairy Tales to stop Ritsuka from retrieving. He doesn’t arrive in time to stop that, but he is able to stop Ritsuka’s memories from being erased. Shocking everyone with his survival, he reveals the scrap was a trap. Reines and Mash doubt it’s really him, but he asks them how could a Servant leave a corpse. He then explains he used his special properties as a Pseudo-Servant to fake his own death. He admits it left mostly without Zhuge Liang’s power, but it allowed him to continue investigating relatively unimpeded. After getting annoyed at his inferiorities, he explains the final scrap is why he needed to keep a low profile. He then reveals how the Singularity’s vast mana increased the normally inefficient energy drawn from their memories. He explains using the scraps caused the Singularity’s vast mana to encroach on their memories and fabricated them, which is the enemy’s goal. He suspects Ritsuka’s memories were stolen from them from the moment they arrived in the Singularity. However, even with their memories stolen though, fabricating memories would be prove difficult since their memories of a particular Servant would resurface if they re-encountered them. El-Melloi II then explains how scraps were placed in certain locations for Ritsuka to retrieve to rewrite their memories. He continues the first two were their original memories while the last one would fabricate them. He concurs with Gray that Chaldea would know if Ritsuka’s memories are true. He asks though why they’ve been only receiving transmissions from Mash and explains the enemy needed someone Ritsuka absolutely trusted to guide them. Reines deduces the M in El-Melloi II’s message was for Mash. El-Melloi II reveals the Mash the group has been talking to is a fake. After the fake Mash blocks communications, El-Melloi II explains the enemy fabricated the fake Chaldea and Mash in order to get the group to believe in their information reports in order to guide them. He deduces the enemy’s goal isn’t to destroy them, but something to do with the scraps. He cannot deduce anymore though with his analysis of the final scrap, but he says Babbage could help provide a deeper analysis. He then returns to Babbage’s castle with the others.
Back at the castle, the group explains the situation to Babbage, and he agrees to analyze the scrap. El-Melloi II deduces the enemy pities them with good yet ill intentions. He then says they should rest; he gets flustered when Gray offers to brush his hair. Reines then deduces El-Melloi II used his other Noble Phantasm to summon her, Luvia, and Gray as Servants thanks to his connections with them when he needed to fake his death. El-Melloi II reveals the true name of the Noble Phantasm and explains it grants allies the abilities they need. In this case, it turned Reines, Luvia, and Gray into Servants to be summoned into the Singularity. The Noble Phantasm wouldn’t normally have such an effect unless the Singularity’s circumstances put a strain on humanity. El-Melloi II apologizes for pulling Reines, Luvia, and Gray into the situation, as he didn’t expect them to get summoned.
Later, while everyone is resting, he meets with Ritsuka in the hallway after they spoke with Reines. He finds it great that they could connect with her, despite her behavior. He also admires how they’re able to cut through words to connect with the feelings that matter. He then reveals there is no need to resolve the Singularity, as it was already collapsing from the start. He also reveals the Singularity was likely absorbing Ritsuka’s memories to extend its lifespan. He then says they wouldn’t be in this situation if they could contact Chaldea or return there. However, he is determined to protect Ritsuka until the situation is fully resolved. Reines then rushes to retrieve the trio to show them something at the balcony they need to see.
There it is revealed the supposed Clock Tower was actually a fake Rhongomyniad. Babbage reports a large number of steam ghosts and automatons are emerging from its interior, though they seem peaceful for now. He also says the enemy has been driven into a corner now that they’ve unveiled the fake Rhongomyniad. He then gives his analysis of the final scrap, revealing the enemy is related to Chaldea. El-Melloi II assumes them to be a traitor since they knew both Mash’s appearance and mannerism. Babbage then gives the second name revealed in his analysis: Mnemosyne, a system of Chaldea. Reines and Astraea decide to assault the fake Rhongomyniad, but Babbage warns against it with all of the enemies swarming out. Gray says she could clear a path, but she doesn’t have sufficient mana to do so. El-Melloi II suggests collecting the smaller scraps for mana and asks Babbage to provide a countermeasure against their fabricated memories.
Joined by Babbage, the group search for the smaller scraps, and fight through their fabricated memories. Following a battle against fabrications of Ultra Heroine Z, and later a fabrication of Mysterious Heroine XX called Super Heroine ZZ, both El-Melloi II and Gray are left exhausted seeing many Artoria Faces. He wanted them to all wear a hood like Gray does. He then promises to not let any of them meet Gray if they’re truly from Chaldea. He finds it probable that the enemy added possible memories to Ritsuka’s own when they can’t recall such a battle. He also says the chances of Flat Escardos and Svin Glascheit suddenly appearing like Reines wants, even as Pseudo-Servants, are extremely limited. He suggests Reines ask the Chaldea staff or Ritsuka if she needs advice.
Afterwards, the group defeated a fabrication of Gawain at the front gate of Camelot, though his Gift of Nightlessness wasn’t functioning.
Next, they defeat a fabrication of Black Iri, who transforms into a corrupt version of Illyasviel von Einzbern. El-Melloi II only knew Irisviel by name, but he also knows she died at the conclusion of the Fourth Grail War. When asked by Reines how he feels about the fabrication, he replies it was similar, albeit different from his experiences, but he is glad he saw it. He recognizes that things could have been different depending on his actions. He accepts his current self though, even if he succeeded or lost. He’s thankful for the fabrication of letting him understand that. Afterwards, the group defeat fabrications of Heracles and Medea on the Argo. After defeating fabrications of corrupt versions of Benkei, El-Melloi II concurs with Reines that people must take responsibility for their actions. He continues that regrets are their own, but there will be failures on their chosen path. A leader pockets away those feelings, reflects on them, then continues to move forward.
With the smaller scraps collected, Gray uses their mana to create a crystal staircase to the fake Rhongomyniad. El-Melloi II stays behind while Ritsuka, Reines, Astraea, and Gray ascend the stairs, as he has very little of Zhuge Liang’s power left. He then meets with Babbage, who declares he and his troops will defend the citizenry. El-Melloi II finds him strange for wanting to be removed from an irrational dream, yet he is still willing to defend it. Babbage accepts it’s a dream, but he wants to defend the people who live in it until the end, for not doing so would be contrary to his duties as Heroic Spirit. El-Melloi II agrees and offers his expertise as a tactician. EMIYA also offers his help and explains to El-Melloi II that he’s only acting on Astraea’s behest. He wonders if they met before, but El-Melloi II replies they haven’t. Even if they did, he finds it more likely that the current version of himself has no affiliation with EMIYA.
After returning to Chaldea following the Singularity’s collapse with Mnemosyne’s demise, El-Melloi II apologizes for getting Ritsuka into such a dangerous situation. He is displeased by Ritsuka’s joke about Mash being fake, as he doesn’t need to re-experience the feeling he got when he realized there was a fake Mash. He then deduces Reines used Sima Yi’s Noble Phantasm, Unspeakable Formation, on Mnemosyne to make her to see Da Vinci, as she is her weak point. He admits though that he only feels that’s what happened. He is also surprised Gray returned with him, as he merely felt the pull of Rhongomyniad. Da Vinci realizes the Grail must have responded to Gray and Rhongomyniad’s wish to stay with El-Melloi II.
In his first interlude Heroic Spirit Possession (英霊憑依?), he explains his conditions to Ritsuka, Mash, and Romani, and further explains the difference between Demi-Servant and Pseudo-Servant. He demonstrated his abilities, and analyses the Ritsuka's potential as a master.
In his second interlude Boundless Sea (見果てぬ海?), Lord El-Melloi II stares at the beach alone, he seems unapproachable as Shielder and the Protagonist hesitated to approach him. He was disappointed at the sea as he watches the waves of the sea. He explains that even though the sea was named Okeanos because of the Holy Grail, it is an underwhelming experience as the sea is not infinite and doesn't live up to it is name. Fou warns them about approaching enemies. After defeating some monsters, he gifted the protagonist with Gemstones Mystic Code.
In his third interlude The Truth of Readvent (再臨の真実?), Lord El-Melloi II discovered himself turning into his younger self. He blames Stheno and Euryale for his sudden transformation. They travelled to the Shaped Isle, Waver demanded Stheno to dispel her curse. As negotiation turned sour, Stheno send her Golems to fight. Later Stheno and Euryale calls Medusa to fight. Although the goddesses defeated yet again, it turns out that Stheno and Euryale were not involved in his transformation. Waver is determined to find a way to get back to his old form back.
In Fate/hollow ataraxia, Shirou Emiya occasionally sees Rin Tohsaka appears as a Red strategist known as Zhuge Rin (諸葛凛, Shokatsu Rin?). She gives advice to Shirou with reference to Sun Tzu's The Art of War.
Caster is a Pseudo-Servant, strictly speaking he is neither El-Melloi II nor Kongming. For the grand goal of safeguarding humanity, their strengths and weaknesses were combined. Intermixing the two forces, shows the power that is not the original Servant. His combat strength may somewhat lacking, but he compensate for it with intellect. His knowledge, experience, and preparedness have somehow been fused with Kongming. Stheno calls him an A-Class Servant.
It turns out that his transformation to his younger self is thanks to Saint Graph Readvent. His powers as a Servant has not dropped. The form represents "the origin of an idea", it is most appropriate to when Caster fighting in the "leading role".
His skill as a magus actually is not much different from Ritsuka Fujimaru. He can make monster agitated by making their pheromones excited. El-Melloi II uses Bagua Mirrors and Kongming's iconic feather fan in battle. He uses various elemental spells such as fire, earth, wind, ice and lightning, along with various energy beams.
Creation and Conception
 Fate/Grand Order - Caster Profile
Zhuge Liang Kong Ming (Lord El Mellio II) - Caster
Illustrator and Voice actor
Illustrator: Takashi Takeuchi
Voice Actor: Namikawa Daisuke
Noble Phantasm: A
Discerning Eye: A
Advice of the Strategist: A+
Command of the Strategist: A+
Territory Creation: A
Item Construction: B
Unreturning Army: Stone Sentinel Maze
Type: Anti-Amy Noble Phantasm
Originally, Lord El-Melloi II was not someone possessing the caliber and the history that would result in a Servant.
However, the extremely unique circumstances of this Holy Grail War got involved and his summoning was made possible by becoming the vessel of the Heroic Spirit of China Zhuge Liang.
Level 1 Bond
Source: "The Romance of the Three Kingdoms"
Alignment: Neutral Good
A monster of rationalism.
Level 2 Bond
Zhuge Liang is widely known an excellent statesman, tactician from the Three Kingdoms Period of China, and it has been said that his strength played a great part in making possible for the small state of Shu to oppose the longstanding major power of Wei.
Level 3 Bond
Strictly speaking, this Servant is neither El-Melloi II or Zhuge Liang. The powers of both parties has mingled together, so abilities that cannot be found in the original Servant are being displayed. Also, thoughts and emotions conform with those of the vessel, El-Melloi II.
Level 4 Bond
Discerning Eye: A
Personal Skill. An ability that finds its cause not on Zhuge Liang, but on El-Melloi II. An technique that made Human Observation even more narrow. The judgment for in which shape the targeted human will acquire usefulness in the future is extremely outstanding.
Level 5 Bond
Stone Sentinel Maze - Formation of No Return
A legendary military formation set by Zhuge Liang at the occasion when he decided for his army to take flight. Composed by huge rocks, said formation bewildered invaders and drove them to death.
Pseudo-Servant... an Heroic Spirit, that for some reason cannot become a Servant, is summoned to this world by making a human body its vessel. Other than Lord El-Melloi II, multiple pseudo-Servants have been confirmed.
諸葛孔明〔エルメロイⅡ世〕 - キャスター
- Fate/Grand Order - Caster interlude 01: Heroic Spirit Possession
- Fate/Grand Order - Caster interlude 02: Boundless Sea
- Fate/Grand Order - Caster interlude 03: The Truth of Readvent
- Fate/Grand Order - Septem: The Eternal Madness Empire, Section 11: Attack the United Empire
- Fate/Grand Order - Septem: The Eternal Madness Empire, Section 12: Rescue Boudica
- Fate/Grand Order - Fate/Accel Zero Order, ACT-1: The Man Who Knows Fuyuki
- Fate/Grand Order - Fate/Accel Zero Order, ACT-2: Military Intervention
- Fate/Grand Order - Fate/Accel Zero Order, ACT-3: Second Owner
- Fate/Grand Order - Fate/Accel Zero Order, ACT-5: The Meeting of El-Melloi
- Fate/Grand Order - Fate/Accel Zero Order, ACT-6: United Battlefront
- Fate/Grand Order - Fate/Accel Zero Order, ACT-7: Hunting for Bluebeard
- Fate/Grand Order - Fate/Accel Zero Order, ACT-8: Irregular
- Fate/Grand Order - Fate/Accel Zero Order, ACT-9: The King of Knights Returns
- Fate/Grand Order - Fate/Accel Zero Order, ACT-10: The Mysterious Assassin
- Fate/Grand Order - Fate/Accel Zero Order, ACT-11: Strategist's Trap
- Fate/Grand Order - Fate/Accel Zero Order, ACT-11: Strategist's Trap
- Fate/Grand Order - Fate/Accel Zero Order, ACT-12: Discussing the Holy Grail
- Fate/Grand Order - Fate/Accel Zero Order, ACT-13: Battle Royale
- Fate/Grand Order - Fate/Accel Zero Order, ACT-14: The Shadow Chasing Irisviel
- Fate/Grand Order - Fate/Accel Zero Order, ACT-15: To the Greater Grail
- Fate/Grand Order - Fate/Accel Zero Order, ACT-16: King's Pride
- Fate/Grand Order - Fate/Accel Zero Order, ACT-17: Wish of the Three Founding Families
- Fate/Grand Order - Fate/Accel Zero Order, ACT-18: The Fallen Grail