name: Kotomine Kireiage: about 35 years old
nationality: Japanese
profession: priest and manager of the Grail War
family: none he is completely alone after the death of his father in the previous Grail War.
likes: evil, killing innocents, Maabo Doufu.
dislikes: emotions, heroes, good
magic powers: He's a healer but being the teacher of Rin he also has knowledge of magic. Lately it's revelaed he's an Exorcist of the church.
servant: Lancer (obtained by killing his previous master) and Gilgamesh (mantained from the previous war)
personality: Kotomine Kirei can't be defined as a mad person although his intentions are somehow incomprehensible and twisted. He has always found some pleasure in acting evil, although he has always realized what he was doing and what he still does. Knowing his nature and understanding that he couldn't find any satisfaction in acting good, he wanted to find a reply to a fundamental question to his existence. He simply wanted to know if, considering his attraction for evil his nature could really be considered as true evil. This is what he really wants to find out and the main reason why he joined the Grail War (although rules were against him) cespite being its Manager. He can't tollerate many things, although he's kinda passive and not too keen in anything special. He has always despised people acting righteously and especially his past rival, Kiritusgu Emiya since he could do something that wasn't accorder to him: having emotions and controlling or suppressing them to accomplish duty. He can't understand the meaning of the word "love" and although he tried to abandon the evil path by loving a woman, he couldn't resist and killed her with his own hands (as he badly wished). He doesn't really like people and he tries to be by himself most of the time. When he's with someone he can't keep his own thought and tells things directly withouth thinking people could feel uncomfortable and without realizing if he offends other's feelings. Kotomine Kirei isn't an attractive person and he doesn't seem to dislike being left apart, probably because he doesn't care about everyone else than him, or because he just want to concentrate on his aim. We don't really know if something good lies within him, since he sometimes help people with his healing powers and it seems he doesn't do it because he's oblidged by somebody.
spoilers warning !!!
personal story: Kotomine Kirei is the son of the Manager of the previous Holy Grail War and having survived the previous conflict he ha sto inherit the position of his father and become his successor. We don't really know what he did in the past 10 years, although we know for sure he was waiting again for the Grail War to spread, to have one more chance to take part at it. That's probably why he used the oprhans who survived to the great fire to sustain Gilgamesh's mana, in order to keep the servant in this world and having more power compared to the one of any possibile master (that could be explained since servants can't keep the memories of their previous wars, in order to not get more experience than the others). He also managed to kill Lancer's master and get him by his side, although they strongly despise each other. He's also Rin's teacher (in magic matters) and despite his hate for people he seems he doesn't dislike her that much 8he made several gifts to her, like Azoth and the clothes Saber is usually wearing in daylife. We only know more about him in the last scenario, when his past his revealed. We discover that he was killed in the previous war, but he was somehow "resurrected" due to the evil spirit tainting the Grail. He's of course the main villani of the story and his real purpouse is to spread the evil content of the Holy Grail (the entity that tainted it in one of the previous conflicts) and see how it would affect the world. In Fate he tries to hide his real intentions giving advices to Shirou, but he's eventually discovered. As his real intentions are revealed he tries to kidnapp Ilya since she was the Vessel of the Grail and use her in the final ceremony. He's eventually defeated by Shirou and killed with Azoth. In Unlimited Blade Works he's again the main villain plotting against the heores and decided to accomplish his twisted mission. This time he's killed by Lancer, as he tries to get rid of his unloyal servant, oblidging him, through a command spell, to kill himself, but he's ironically stabbed too by him. In the last scenario, Kotomine is once again an enemy, although he sometimes help Shirou and Sakura and only reveals his intentions in the final stages. He badly wants to free the tainted essence from the Grail and he ends up in fighting against Shirou and being killed by him .