Oh yeah, he still gets nightmares because he's seen some horrors. And that was before he even got into the military! Poor guy's life has been a disaster since he was a little kid.

So pretty much, get him on missions with other folks and thread some stuff out so people can see he's being stupidly reckless when on missions and not acting like his normal self? Only drawback there is missions are normally handwaved and all. And he'd need to be forced to work with people because he prefers working alone.