[@Lucifers 666]

Well there is little information about society at large. I'm guessing we are operating in a high fantasy setting.

But the rough cut, which my be totally changed, is that the character worked as a surgeon or apothecary. Trying to learn and understand death itself prior to service to the Dragon. He learned a great deal about the body in doing this and worked with the military of (faction A) during the conflict with (faction B) and applied his knowledge to helping the wounded warriors while learning a huge amount about disease and corruption, such as the infection of a wound or gangrene. 

Again, very rough cut idea.