"I'm going to teach you how to be as amazing as I am!"
Hmm ... maybe this wasn't said, but I think they both knew that Brian was Justin's mentor:
- Brian takes Justin's virginity, but he is gentle, takes an interest in Justin's sexual experience, teaches him about rimming - in short he teaches Justin a LOT about sex from 101 onwards.
- Then when Justin asks Brian for business advice in S2, Brian makes a flippant comment about having already given him a lot of advice. Brian's been around the block in business as well. He's been to college. Justin can't help but be influenced by him.
- Brian influences Justin (for the better) about the importance of being independent, committing to and following through, making life changing decisions based on what Justin wants, rather than what others want him to do (which college to attend).
Brian did not want Justin to go the "Stepford fag" route, and he doesn't (at "least, not at the end of S5). I wonder if Justin would have qualified for "the best homosexual you could possibly be" if he hadn't changed his mind about marrying Brian.
Anyway, I'm sure that Brian knew he was teaching/influencing Justin, and Justin was quite happy to be taught/influenced.
I think "you're the best homosexual you could possibly be" is a bit meaningless though. You could be not much of a homosexual and still be that, if you know what I mean. Also, isn't being the "best man you can possibly be", including being out and proud and all, more to the point.
Side note: Justin was braver and more grounded than Brian in some ways, and so was able to influence Brian too.