Thank you! I'm glad you found the story. Thank you for commenting.
Giles is indeed justified in harboring resentment. Just because he's one of few adults on the show does not mean that he's perfect or unemotional. And he has every right to distrust Angel.
I like slash, but, yeah, I don't think that antagonism always has to take a slashy direction. (Although angry slashy porn usually gets more feedback than any other kind of story...)

Cheers!