Hmm... I'd say Gaara takes it. Growing up while having people trying to kill him, hits being out on by his own father, growing up thinking his mother and father hated him. Kids would never play with Gaara out of fear. His own siblings kept away from him. There's also Shukaku in him too, constantly trying to take him over and making him kill people cause he just didn't have the willpower. Eventually Gaara just gave in because he couldn't handle it anymore. Good thing Naruto came around*_*
Edit: You probably made this because of what kingHashirama was saying on your other thread Lol