Xehanort was irony. He was the last laugh, that sick feeling in the pit of your stomach, fists clenched too tight, humorless, hysterical chuckles.
Xehanort was dark, pervasive darkness, not really funny at all in the same way that misfortune isn't funny (you don't want to laugh but you do anyway, because it's so goddamn sad, so pathetic, that if you don't laugh you'll cry and break down and give up and then he'll just laugh at you instead, because he's irony and it's his god-given right to laugh).
Xehanort was irony, sick, twisted irony, irony tainted by dark humor.
A/N - Okay, now I'm officially un-grounded. So this weekend (and probably the early part of next week) I'll be review-replying and PMing and updating like crazy, okay? (: