Two siblings from Greek mythology, Dioscuri CastorWP (ディオスクーロイ ・ カストル, Diosukūroi Kasutoru?) the elder twin brother and Dioscuri PolluxWP (ディオスクーロイ ・ ポルクス, Diosukūroi Porukusu?), the younger twin sister. Castor was trained by Chiron, noted among fellow "shining stars" students like Heracles, Achilles, Jason, and Asclepius. They/he was then sublimated as the GeminiWP constellation.
Once there were two twins who ascended to the heavens above, becoming the shining constellation of Gemini.
The name Dioscuri holds the meaning of “child of Zeus”. Within the 3rd century BC book “Catasterismi” it is said that the constellation of Gemini is the Dioscuri, and that the twins were respectively called Castor and Pollux. It is in Laconia (the southeastern part of the Peloponnese peninsula) where not long after being witnessed together they ascended to the heavens. A love surpassing what was held between this brother and sister was never to be seen again. Out of wanting to forever remember the close relationship the two held, Zeus created a constellation using the stars of two independent formations, thus naming the constellation Gemini.
Originally the twins were worshiped as “nimble horsemen”. Also, Having been thought to be the stars that light up the night skies after a passing storm they were worshiped by people. However, as time passed people ended up believing that St. Elmo’s Fire which would appear on a ship’s mast in the middle of a storm was the true manifestation of these divine twins.
The divine twins were the Patrons of sailors. In the beginning they were worshiped for swiftly saving people from danger, however, from their role in “The Argonautica” as part of the Argo’s crew they have come to strongly carry the personification of being Gods that rescue sailors. Known by many names such as “The Two of Royalty”, “The Two Pillars”, and many others the twins never actually held their own true names. Leaning on their ancestors, it is thought that they ended up taking on the names and history of “Castor (Kastōr)” and “Pollux (Polydeuces)”. Within the stories of “The Argonautica”, “The Iliás”, “The Myths of Hyginus”, “The Metamorphoses”, “Bibliotheca” and many others while one of them is the child of Zeus they are not actually gods. Rather, they are shown as human beings prior to them becoming a constellation.
The Dioscuri are always together without ever being a moment apart, the inseparable twins. “They are unable to be apart.” could be said to be an understatement as the two of them are “One Heroic Spirit that is formed by two.”
Being at their core an ancient Divine Spirit they manifested with special traits at the time of their summoning. They exist as one while residing in two separate physical bodies in which can be found the traits of different classes. As for the explanation…
The humiliation the older brother Castor, who became the child of a mortal without the blood of Zeus in later legends, felt falling from the gods to the human world turned into hatred, resulting in his manifestation as an Avenger. Living a life with a body that cannot be hurt and doing battle with fierce swordsmanship, the immortal one who bears the bloodline of Zeus, Pollux has appeared as a Saber. Recorded in their Spirit Origin is that of the Saber class, however, to be more accurate the two of them are what is considered a double class servant. Though what could be thought to be the case of an exception, the special traits the two possess are that of a Divine Spirit servant.
The sword Pollux wields and the discus Castor wields are made out of invincible Adamant, the so-called divine steel, was used as the vessel for the materials, with Odysseus's Aigis armour being made out of it, as well as Achilles' shield and armor. Pollux is said to be skilled at boxing.
- Magic Resistance (A Rank)
- Riding (B Rank)
- Mad Enhancement (B- Rank)
- Avenger (B Rank)
- Self-Replenishment (Mana) (D Rank)
- Oblivion Correction (B Rank): In later legends, the divine blood of Zeus the twins had was forgotten, however it was recorded in Castor's Saint Graph, and not Pollux's, who was recorded as a Saber. Being summoned together under the Saber Class, Dioscuri is the only non-Avenger Class Servant with this skill.
- Divine Core of the Twin Gods (B Rank): A skill that both possess. As ancient divine twins it should have possessed the power of A rank. However, from being affected by the growing legends within Greek Mythology as time passed the skill ended up at the power of B rank. In particular, it is thought that a major effect came from the legend of the brother Castor being "one without the blood of the Gods".
- Stars of the Chief God (A Rank): Displaying the way of Divine Twins through them existing together as one and becoming a constellation.
- Guardians of Navigation (B Rank): Calling forth protection for those who sail the waters. The existence of Divine Twins brings forth hope for those in danger and energizes them from their very Souls. While seeming to only be a skill to help those navigating storms, it is actually a skill that also exemplifies the charisma of a strategist at it’s core.
- Mana Burst (Light/Ancient) (A Rank): A skill that displays their being the light which illuminates the ocean way “St. Elmo’s Fire”. In many ways similar to the subspecies Mana Burst that some Saint type Servants possess, it is able to release Magical Energy in the form of strength increasing light.
Part of the profile in Fate/Grand Order was revealed to have been directly copied from a Japanese research source, leading to a change in the text and apology from TYPE-MOON staff and Delight Works.
- Fate/Apocrypha volume 2
 Fate/Apocrypha material - Encyclopedia: Archer of “Black” [Servant], p.159-160 [T]
Archer of “Black” [Servant]
One of the Servants of the Black camp. His true name is Chiron. He is a centaur—a half-human-half-horse race, and he is a famous great sage in Greek myth.
He has a calm and gentle personality, but though he treats his Master with respect, he won’t hold back on advice if it’s for the sake of his Master. He never scorns or despises others regardless of whether they are enemy or ally, and he is exceptionally calm among the intense and passionate heroes of Greek myth. He acted as the strategist of the Black camp and continued to support his camp day and night right until he took part in the final battle.
Usually, centaurs are considered both as great huntsmen who effortlessly use bows and arrows while running with their horse legs and as savage monsters who would steal anything and everything. It seems Chiron alone is regarded as a “sage” that stands out as an exception among them.
Chiron was born from Cronus, father of the head god Zeus, and Philyra, the goddess of a certain island. However, because Cronus had copulated with her while she was turned her into a horse, Chiron was born as a half-human-half-horse centaur. (There is also the theory that they were attacked by Cronus’ wife Rhea while they were in the middle of copulating and Philyra turned into a stallion in order to run away.) Balking at the idea of giving milk to a monster like Chiron, Philyra changed her form into that of a linden tree.
Though he was never loved by his mother and father, Chiron became a sage that excelled in all forms of knowledge as he grew up. This is not necessarily unrelated to the fact that his mother’s name “Philyra” means linden tree. The leaves of linden trees can be used as restoratives, and the tree bark can be used in divination or as written boards.
After becoming an adult, Chiron began to rear the “future heroes” who implored for his tutelage from all over Greece. Besides Heracles and Achilles, the heroes who received his teaching include those like Asclepius, who later became the god of medicine, and Castor, who was sublimated as the Gemini constellation. Jason, the leader of the Argonauts who enticed Medea, is also one of his students.
On a certain day, someone shot a poison arrow at him while trying to stop a dispute between centaurs, and the poison continued to endlessly make him suffer due to his immortality, until he became the Sagittarius constellation by returning his immortality to the gods and finally received salvation. His wish for the Holy Grail while participating in the Holy Grail War is to regain his immortality. To him, it is the only gift he received from his parents.
As a Servant, his stats have received a slight rank down due to giving up his immortality and transforming his legs into those of a human, but even then he boasts of specks high enough for him to be called a first-rate Servant—to an extremely abnormal extent in a certain sense. In the first place, it appears that he taught not only swordsmanship, archery and horse-riding, but also wrestling techniques, so he is relatively experienced in moving with human feet.
With the combined effects of his skills, he can even utilize a pseudo-form of future sight, making him truly all-purpose in his abilities. If he has a weakness, it is that he lacks a decisive trump card. Against the brute force approach that throws away all wisdom or intelligence, his strong points fade away.
He deeply loves how weak and insufficient humans struggle despite their insufficiency and still try to move forward, so even if he was summoned as part of the Red camp, he would have definitely rebelled against them with the resolve to die.
Though if he were to describe it himself, he would merely answer, “This is my arrogance as a teacher, as embarrassing as it is”.
In the novels, he was mainly focused on his fight with Achilles outside of his light skirmish with Mordred. After all, Chiron was the only one capable of harming Achilles. That battle was such a great joy to him that he even forgot his true nature as a Servant, but he stood back up as a Servant again at the moment of his death and accurately dealt a fatal wound to Achilles.
- Twitter apology and Fate/Grand Order website apology