The Master is self centered but self aware.  I really like him, I think he's awesome even though he talks a bit too much.  He accepts his life and all that has come, but I feel like he probably tells his life story to strangers time and time.  The set of keys he owns give him the ability to be instantly informed on any new occurrences in the clinic, allowing him to have a status similar to that of the nurses.  He has false authority as well as seniority.  He's open, honest, sharing, a very genuine character and I look forward to getting to know him better.