In 2003, she and the rest of her squadmates (save Agatha) were seriously injured in action during an unspecified mission, putting them out of commission for a week. However, she eventually recovered, and was present when Mike Warner was introduced to the rest of the squad in the hospital.
Rachel is an IU undergrad living in the Clark Wing of Read Hall, and first appeared during the Whiteboard Dingdong Bandit arc. She rooms with another Rachel, and she is considered the Other Rachel of the two. (This is how she is tagged in the strip's archive.) She really should take the trash out once in a while.