Brian started out as the loyal best friend of Peter, and something of an intellectual. The fact that he was smarter than his owner/best friend was never an issue, in fact it worked. It worked really well at times. Remember Brian taking a front row seat for one of Peter's outrageous lies and later telling him "You are the Spalding Gray of crap" in "Chitty Chitty Death Bang?" Those are the times when Brian worked. When he began seriously working on that novel of his? That's when things really went downhill. Yes, the show was using him to prove a point now and then, but in the process, he became unlikable. That's never something you want for a main character. The only saving grace for Brian is that he does still work as a best friend (from time to time) - just not for Peter. It's really Stewie who Brian is best friends with these days.