Megaton settler

The Megaton Settlers are Wastelanders who have settled in Megaton. They are Non-player characters, and although speech cannot be initiated with most of these characters, one of them will come and tell you that they are grateful for everything you've done for them and give you a present, which can includes (but may not be limited to) food, meds and ammo. This is only if you have good karma, and only if you haven't blown up Megaton. This will happen repeatedly every so often.

History
By initiating dialogue with Manya and ask her about the history of Megaton, she will tell you that many Megaton residents came to Megaton to get into Vault 101.