Things I like about the BJ relationship
That’s a tough question, so I’ll try to layout my thoughts in a coherent way. There are many things I like about the Brian and Justin relationship aside from the obvious one, the smoking hot chemistry, and what the OP has already stated. I like how Justin sometimes seems to understand Brian more than people who know him longer, like for example his motives for pushing away Michael at his B-day party or how deep his feelings for Gus are at the episode were Brian debates what to do with his parental rights. I also like how Justin does not immediately jump on the "Brian is an egotistical asshole band-wagon" (again Michael’s B-day episode) but he does not justify and excuse Brian’s behavior at all times either (example demanding an apology for pissing on his work, confront him during the Stockwell arc). He does not enable him like sometimes Michael does. He expects Brian to treat him better and not take him for granted and he goes on to show him this since quite early, when he was still a love struck teenager (King of Babylon episode). Justin knows how to stand his own ground in front of this force of nature which is Brian Kinney, and not many people on the show could do this. Which brings me to: How much I like that Brian starts to respect Justin from quite early because he could stand up to his parents, his teachers and his classmates at a time when Brian himself had not confronted his parents yet. And also I like how he appears to listen to what Justin has to say, like again in the parental rights episodes. For me the Stockwell arc is very indicative: most characters of the show “bash” Brian for his actions, Michael sort of excuses him but Justin does not say anything until Brian catches him printing the posters in which case he confronts him without accusing him or excusing him. And in the end, I think, that his words affect Brian more than anyone else's. I remember once finding a forum where the BJ relationship was bashed a lot. Many people thought that there was nothing more than sex and carnal desire between them. I thought that this was a very superficial judgment. I hope I did not embezzle much this forum’s space with my long post. If so please feel free to delete.