The book details a hero who is picked up on a destroyed Earth (not sure if sole survivor or not). He is smarter, faster, stronger, etc than the other humans.
He becomes part of the military and does special operations. He has a ship that is almost undetectable because you can't look directly at it. He has children who inherit most of his abilities.
At the end of the book his mind is fractured and a local village brings him a girl once a year who he calls by the name of the love of his life. He then sleeps with her. They do this to continue to get children that will have his genetic abilities. I don't know if he's long lived or immortal.