Okay... So, this guy is Hector or Ian Ostermann. He's here because his wife is a professor (Anthropology). She's been here since last semester, so feel free to know her. He came over in March, but he's been seen on campus more this summer, because he got a job in the maintenance department. Part-time only. He will be a freshman in the fall! Again, part-time.
The reason why he's 30 and a freshman is because he was in the Marines. Fighting oversees. He came home because he was ordered to. He left the Marines because he loves his wife (and son - 3 years old) and now it's her turn to pursue her dream. It's not exactly easy to go from Gunnery Sergeant to Mr. Mom. It's also not easy for him to speak about being Hector. You just don't talk about that stuff in the Marines (or at least he didn't). But he's going to try!
Powers? He's a great fighter. He can't beat Ares, but he can win against others. People listen to him, and he doesn't even have to try. But that depends on how well a person likes him. Achilles isn't going to care what this guy says. And, he can't get any minor cuts and scrapes.