The town's overworked and underappreciated doctor, he can be cranky and bitter, but he's always professional. Before Doc came to the town a few years ago, Megaton was without a doctor for a very long time. Before he settled, Doc stayed alive by trading his services to raiders and slavers. Now 54, he refuses to talk about his youth.
Regardless of player's health when initiating dialogue with him, he continues to make remarks that you are in good health and should not bother him. Even coming in with deadly radiation poisoning will still have him remark about how you look fine.
Doc Church is a very light sleeper, and will wake up if you come into his room, even if you are sneaking.