A Multiversal Threat

A young man is secretly chosen by the government to be given a chance to do something absolutely no one has done before, travel the multiverse, he's given the usual talk on how this never happened and he can't tell anyone, the young man accepted, but once he gets the technology and begins traveling, he decides to go rogue, to use this technology to do things he thought he'd never be able to do, slowly gaining powers and abilities he had only seen in fiction, protecting people from the villains of the multiverse, and slowly becoming a multiversal threat.