Keamy had been in the army right? (Prepare yourselves, I'm about to make an Eastenders comparison

) I can't help but wonder if the things he did, and the things he saw may have altered his character into the monster that we saw. Take Sean from 'Enders - the stuff that happened to him in the army has changed him from a fairly normal person to an animal.
I'm not redeeming Keamy at all, but I'm just wondering if the army stuff is important as part of his character development?