Brian is a horrid little brat who likes to torture small animals and throw fits over trivial matters. Apart from these flaws, he's still not a very nice kid.

Brittany gave Brian a white mouse who was to be the subject of a behavioral modification experiment being done by Daria for science class. She got the mouse back, but by then it could only tremble in fear at every stimulus.

Brian likes to kick things and yell when he doesn't get his way, and generally makes a scene in order to get attention. It is possible, even likely, that his behavior stems from a combination of his parents' divorce, and his father's lousy parenting - Mr. Taylor definitely shows favoritism to Brittany, and regularly belittles Brian.