And we've now met Tyler--Damien's brother--and Lockhoft. For now don't question how she became a colonel, or a marine. for now she just is; and it will be explained. just not now. so just go with it.
Personality wise, Lockhoft is cold as ice, and rumor has it that she's killed zombie's with her bare hands.
Tyler is more of a side character who just does shit, usually a boss.