10 Video Game Heroes Who Became Villains In The Sequel
9. Dr. Madison Li - Fallout 4
The primary antagonists of Fallout 4 are the Institute, an enigmatic group of scientists that conducts inhumane experiments on the population of the Commonwealth.
The group is hidden deep underground and shrouded in mystery, and yet one of their members is actually a familiar face.
Dr. Madison Li is a researcher who makes her initial appearance in Fallout 3 as a potential ally. She works on Project Purity, a water purification effort in the Capital Wasteland, and depending on your choices, she can even help you complete the project alongside other scientists in order to make the wasteland a better place.
However, despite Dr. Li's positive impact in Fallout 3, she ultimately becomes yet another Institute lackey in Fallout 4, performing cruel research on the surfacers in the name of "science."
This change is a result of Madison Li's distrust of the Brotherhood of Steel, which forces her to leave the Capital Wasteland and seek refuge among like-minded (if not more sadistic) Institute scientists.
Funnily enough, you can actually convince Dr. Li to leave the institute and rejoin the Brotherhood, but considering she builds a giant death robot for her new/old friends, it seems she's doomed to become a villain in the sequel no matter what.