>>2180406Gil wasn't corrupted by the grail actually - it's stated quite clearly that he managed to survive the grail mud and is still sane where most others wouldn't, it's just that that's how he's always been. Gil just views the world differently as a result of once ruling over it. At his core, he actually loves humanity, but is disgusted with the current state of it. His first impression at the beginning of Fate/Zero was less than favourable and he's been bitter since.
I've been assuming you know what Fate/Zero is, but if not it covers the previous Grail War. Make sure you go through it once you've finished with FSN.
