I know your cousin is mean to you, but (accidently) trying to feed diddykins to a giant python is a little harsh!

Honestly, these chapters did a lot to put a framework around who Harry would become. Being intimidated and controlled in the fashion of the Dursleys resulted in Harry's attitude when he starts to experience freedom at Hogwards (and his "certain disregard for school rules". Also has a bit of a chip on his shoulder for anyone that tries to bully him, or his soon to be friends.