My protagonist is at the raw age of 22 but was 17 when they enlisted and 21 when they deployed.  He grew up in small town Iowa with little to no parental guidance.  When his sister was home, she instilled her own version of discipline, but for the most part she was her best friends adopted sister.  While his family is nowhere near exemplary, he is more protective of them than he is of himself.  The only person allowed to criticize the situation is someone from the sister’s adopted family. 

As far as education goes, he doesn’t value “book smarts” but is incredible street savvy even if they won’t recognize it.  He did passably in school at best, but in the military, his superiors selected him for field paramedic and leadership positions.  The one thing he wasn’t prepared to deal with overseas was the psychological factors.  He barely passed his psych evaluation before deploying because in some ways he can’t stop thinking, yet he knows how to keep those thoughts to himself out of what he sees as self-defense.

He has had many sexual encounters, but only one real relationship.  However, he doesn’t recognize this because his parents never demonstrated a healthy relationship.  His father while harmless was an aggressive drunk, and his mother while a good person was eager to please every guy she ever dated.  In the same way his psychology didn’t prepare him for deployment, it also did not prepare him for the intimacy of telling someone everything or the companionship of being a team.  This lead him to be cheated on, stolen from, and elsewise mistreated by the people in his life and to push away anyone who wouldn’t do those things.

The culmination of all of this is the molded exterior that says things like “this was my favorite.”