He's the main antagonist in every ufotable adaptation of fate also the most complicated character to understand like Omni man
SPOILER
he dies in everyone of them
Fate enthusiast 1: Who's your favourite character in the fate?
Fate enthusiast 2: Kotomine Kirei and you?
F en 1: I would have to go with Rin she's just badass and best girl
F en 2: Um...Saber is obviously superior
F en 1: No Rin is way better, she doesn't need to drain your energy and she can also protect herself
F en 2: Saber can do the same also she's the king of britania and has Excalibur also she's the strongest class
F en 1: Wasn't she like a familiar which means she isn't even the real king?
F en 2: Listen here you little shit if you can't appreciate how amazing she is in gonna beat the shit out of you
F en 1: Wdym??? Rin acts so cool all the time , she's smart, cute, strong and IS AN ACTUAL FUCKING HUMAN BEING
F en 2: oh now you've done it motherfucker im not gonna take your shit anymore, by the commandment spell Saber come here
F en 1: fine then, Archer you in position
Archer: I've been waiting for a while now i knew it was gonna go that way
Saber: same
F en 2: Enough talk Saber go take down Archer asap
Saber: Understood
F en 1: Archer try to avoid using close range combat
Archer: fine
F en 1: so it's just the two of us now
F en 2: Just like i wanted. I already knew you set him up and be ready for combat so i didn't want to risk attacking while you're on your guard
F en 1: i knew that you were gonna know about me being on my guard so i talked with Berserks master and he's already here
F en 2: shit!
F en 1: aaand you take 8 points of damage