Its really nice seeing people being so lovely. Getting great help here when i was making a character was big part of why i took to the game so well.
I think the suggestions about PTSD and family could work really great in game. In the league there were two people who independantly wrote stories about loosing family, and a major thing for their game was deciding that they were each others family.
It gave a huge emotional payoff - to the point that whilst we were talking OC on a thursday night, years later they mentioned it as one of their highlights from a lifetiem of larp.
At my first, I had a really great RP experience when my character found a preist to talk through his head problems with.
In terms of making background work in uptime I think the big questions are about what you would find fun, what you would be willing to do to make your back story visable to the people around you. Flinching at knives, carrying round manacles etc as mentioned above are all great ideas - but in up time you often have to choose between the thing that would advance you in game (e.g. defeating the person with the knife) and doing the thing that is going to make your characters backstory apparent to the people around you (flinching).
One of the fun things that playing a character like this can open up is that the best RP experience might come from doing the thing that you know as a player might be the worst idea. e.g. always sending your military unit to attack the druj no matter what other opportunities are or having an arc that starts with you consistently reacting based on your tragic past - but as you heal from that slowly starting to act more sensibly.
I think you definately have a really nice idea for a character here and they will likely be fun to play and interact with.