Buzz is the stereotypical meathead older bro…and not just because his parents saddled him with the unfortunate name Buzz. (Is he a Lightyear? Thought not.)
He's an obnoxious jerk who devours a cheese pizza set aside specially for Kevin before pretending to barf it up all over him, and who spreads a nasty rumor about their kindly neighbor Old Man Marley.
The pizza incident gets Kevin banished to the attic bedroom, which makes it easier for the family to forget about him when they fly to France. So you can pin part of the blame on Buzz.
A typical Buzz comment comes when Kevin asks him if he can sleep in his room, to avoid having to share a bed with his cousin Fuller. Buzz replies,
BUZZ: I wouldn't let you sleep in my room if you were growing on my ass!
His room isn't exactly the city of brotherly love. Maybe that's part of the reason Kevin ends up trashing it, jacking Buzz's life savings and accidentally smashing the shelves in his room.
While in France, Buzz continues to demonstrate his stupidity. When his sister Megan asks him if he's worried about what will happen to Kevin when he's home alone, Buzz says,
BUZZ: No, for three reasons: A, I'm not that lucky. Two, we use smoke detectors and D, we live on the most boring street in the whole United States of America, where nothing even remotely dangerous will ever happen. Period.
He goes from A to two to D—classic Buzz.
Yet, compared to the burglars Kevin has to deal with, Buzz must be a pretty low-key enemy. He's even impressed with Kevin for surviving alone. Of course, he's enraged when he discovers that Kevin trashed his room.
But, at this point, were confident that Kevin can deal with him. Kevin has booby-trap making skillz…and he knows how to use them.