Agnes was originally born as a tribal, but her family wanted to join the NCR, so they moved there and she was sent to the university. She mostly studied biology, but also acquired some medical experience (hence she is a doctor). In 2250, she met Goddard, another scientist from the NCR at Hoover Dam. She had left the NCR because it was not safe there anymore, and Goddard had left to find a way to get to the Boulder Dome.
After all was said and done, Agnes had teamed up with Goddard, and was being escorted with him to the dome by means of Eddie Galenski's truck. Once there, she assumed the role of taking care of the rest of the plagued scientific team, as well as helping with repairs and morale.
Agnes has not appeared nor was she mentioned in any published game. She was to appear only in Van Buren, the canceled Fallout 3 by Black Isle Studios. It is not certain if she will appear in any future Fallout game.