My first attempt at making a video on my computer, It's capable of better quality (i'm sure) but i'm not, yet. Also, note the good voice clips i found of stewie in the later episodes BOTH contained Brian. As early as the second season you see a lot of Peter-Brian dynamic and less Stewie-Brian. With the rise of the "Road to.." Episodes, there has been a rise in Stewie-Brian moments. Every episode now seems to have a few scenes involving exclusively these characters.
If I can find a good enough argument/theme, I might have Family Guy as a thesis topic.