This morning the scene in season seven where Xander is joking around that he wants to be gay because he seems to only attract female demons and Giles snapped at him popped into my head. The logical reason for Giles' reaction being that he's offended because he's a closet homosexual, or at least bi-sexual.

That lead me to think about how most of us assume that he and Ethan had some kind of sexual relationship when they were young, and it's a theory I love. But it got me to thinking... What if the reason Giles hates Ethan so much now is because he had been in love with the guy that Eyghon killed, Randall.