Vegeta trained after the fight with Majin Buu, etc. His power level rose, and he achieved Super Saiyan 3.
In Dragon Rage, he is one of the main characters. He fights his brothers Xirus and Cade. They both turn out dead, but Cade is revived.
His Structure in the Story.
Vegeta in the story is going to be villanious, AGAIN. But just to make the story more fun, and fanon.