5. Brian Was An Audience Surrogate
Despite his many flaws and his tendency to get into as much trouble as the rest of the Griffin family, Brian's most important quality is that he's the most
normal. We need a Brian character in this vein because it gives us somebody to associate ourselves with - despite the fact that he's a dog, he was ultimately the most rational member of the cast. He was... the most human, if you will. The fact that there was somebody like that around made it all more enjoyable to watch. When Peter gets into a crazy scheme, it's Brian who says what we - the audience - are thinking. I suppose it started off as something of a running joke that Brian was the most "sensible" member of the family, despite the fact that he was a dog. Great - that's funny. But how could MacFarlane and his team have missed the fact that Brian is an essential element inherent to what makes Family Guy funny? The fact that he was essentially more human than the human characters was what brought us round to him. Whether you realised it or not, or thought Brian was fundamentally a "boring" character, he was necessary to the equation: our kindred spirit and straight man.