I like that Jack doesn't (usually) drink, because I don't and he may be the only slashable boy I have that in common with... that said, I'm not calling anyone on it because 99% of fic is AU anyway.

My theory, which is mine, is that he doesn't drink because so many of the people he knows DO, and so he can take advantage of them right and left. (OK, admittedly that's rather an evil!Jack characterization, but it makes me smile.)