There's a story that I must've read over a dozen years ago now, and every so often when people ask for a particular type of story I'd mention it if I could remember the name.
Young teen (who I believe was a inventor similar to his father) loses rather wealthy parents (I believe they were weapons contractors) to violence. He goes to ground in the woods, having been trained by a native warrior (either relative or best friend of parents) then makes contact with some army buddies of his father before restarting his life (and trying to track down and gain vengeance upon his parent's killers).