Everything Has Changed (A Chuck Fanfic/Charah Story)

*DON'T HAVE TO WATCH THE SHOW TO READ THIS! IT'S AU*
Sarah Walker is the CIA's best. She's Director Langston Graham's wildcard enforcer and she's been with the agency since she was a teenager.
After years of service, she is partnered up with Agent Charles 'Chuck' Bartowski, a guy who is sweet and nerdy but has only been with the agency for a few years.
As she spends more time with Chuck, she feels herself getting softer and opening up to him about parts of her difficult past. She didn't expect to fall for him though since the first rule of being spy is to never fall in love...