Kayneth El-Melloi Archibald (ケイネス・エルメロイ・アーチボルト, Keinesu Erumeroi Āchiboruto?) is the Card User of Lancer in the Fifth Ainsworth Holy Grail War. After dying, he has been placed in a Doll body in order to participate in the Holy Grail War.
There is not much known about this version of Kayneth and it is unknown if he was killed before, during or after the Fourth Ainsworth Holy Grail War. After being brought back to life, the Ainsworth family gave him the Lancer Class Card to stop Shirou Emiya who was defeating all the other Card Users of this War.
He kept his original appearance. When he installs the Lancer Class Card, he obtains Cú Chulainn's set of armor with his outfit's coat-tail and Gáe Bolg. Alongside with it, the left part of his body is covered by his Volumen Hydrargyrum.
At first glance, he seems to have kept his personality without having some sort of damage to his ego. During his fight with Shirou instead of his the powers and Noble Phantasm granted by the Lancer Class Card, he only relies on his Mystic Code, probably because of his pride.
Fate/kaleid liner PRISMA☆ILLYAEdit
In Fate/kaleid liner PRISMA☆ILLYA 3rei!! manga, when Shirou was telling the story about the Fifth Holy Grail War, Kayneth makes a quick appearance as one of the last Dolls Shirou confronted before having to fight Zachary Ainsworth. In Fate/kaleid liner PRISMA☆ILLYA Oath of Snow, their encounter is extended showing how their fight went.
They are shown fighting on containers, situated in a place that seems to be a harbor. After clashing a little, Kayneth blocks all Shirou's attacks making him back off. Kayneth notes that EMIYA, as he could remember, is the form of Shirou's future self. As Shirou doesn't answer him, he decides to activate his Volumen Hydrargyrum with the spell Fervor, mei sanguis. (沸き立て、我が血潮, Boil, my blood.?) and attack his opponent with his Scalp (斬?) command. They end up clashing another time and draw closer.
He then says that he heard that there's no concept of time in the Throne of Heroes and supposes that this is also possible. Shirou interrupts him by pushing him back and he counter-attacks with an another Scalp command. Shirou continue his attack, by rushing towards him and throwing two pair of Kanshou and Bakuya. Kayneth claims that such weapons won't be able to reach him, blocking them and using his Mystic Code to strike him down but Shirou dodges it and then throws a regular Bakuya.
Kayneth confident, tells Shirou that he already said that it was no use and proceeds to block the sword but he is stabbed by it as Shirou propelled the weapon with a Kanshou in the Overedge form, breaking his guard and inflicting him a fatal injury. Kayneth dying, asks Shirou from where his power comes and what he is, before leaving the Doll body he was into. Shirou responds that he made a pact with Alaya, making him a Guardian of Humanity.
Kayneth appears to maintain a degree of his intelligence, allowing him to discern the identity of Shirou's Class Card as his future self. He wields Gáe Bolg, though he did not show off its Noble Phantasm ability.
His attacks and defence are used in tandem with Volumen Hydrargyrum, which he uses to block strikes that he does not or to attack with with multiple blades at once from either close or long range, though his usage of the Mystic Code is less advanced and versatile than his Counterpart's control.