I remembered reading a novel that has the following plot points:
- The protagonist is a human male
- coming from a planet that provides mercenary services
- he is the sole survivor of the planet
- the rest of the planet died because of radiation poisoning from imported grain(?)
- sent by some evil faction(?) because the mercenaries are detrimental to their plan
- he was 'abducted' by a group of people known as the overseers(?)
- his bone -- damaged by radiation -- is replaced with an unbreakable stuff
- he has a companion, a female from another galaxy, whose appearance is not humanoid but more like a bat(?)
- he can 'talk' with her through telepathy
Plot points I'm not really sure about, I've marked with a
I think I read the novel (borrowed from a long-defunct library) sometime in the late '80s or early '90s.
If anyone can give any hints/clues as to what that novel was, I'd be very grateful...