Vegita

Vegita is basically an evil Saiyan, he is totally strong willed and full of pride, willing to die before losing his honor. He is also extremely hard working, always trying to get better at fighting since he is extremely bloodthirsty and unwilling to admit defeat. He slowly changes. His primary reason for getting better at fighting is that at some point he wants to fight Son Gokou, and he is unable to accept the fact that Gokou is more powerful then he is. When he saw Gokou turn into a Super Saiyajin and defeat Frieza he became extremely jealous and trained his tail off, finally becoming a Super Saiyajin. He only had a short moment of happiness after defeating #20 before #18 took him out. His first big change occurred when he interfered with Son Gohans battle with Cell which caused Gohan to be seriously injured. He actually apologized to Gohan for that one. After that he changed his ways. Before he went to sacrifice his life in an attempt to destroy Buu he told Trunks that he was sorry that he hadn't given him as much attention as he had deserved and that he cared about him. During Gokou's final battle with Buu he realized that Gokou's pureness is what gave him his power and he went through a total change after that.