Ben Tennyson is the main protagonist in Ben 15.
Ben at age 11 dreamed of being a hero. With his newfound Omnitrix, he could accomplish that dream. However, he soon realized that people didn't like him. They called him a menace or a freak. After 4 more years of pure hatred towards him, he decided to go rogue and not help anyone anymore. Alien attack on the city? No, won't go. Giant frogs eating people? Nada. He begins to invent things on his free time, and becomes so skilled, that he figures out how to hack the Omnitrix, and even upgrade it. He just needs the parts.
Ben's Grandfather, Max Tennyson, and Cousin, Gwen Tennyson, were always nice to him. They never fought, and always supported Ben no matter what. Ben's best summer ever was when he was 10 years old. When he found the Omnitrix, his formerly-revealed Plumber Grandfather showed him how to use it. He'd vowed to do only good with it. Until now.