Charity was Alan's junior high school girlfriend. She was going to be his prom date, but left him the night before for unspecified reasons.
Twenty years later, it’s revealed that she dumped Alan for Charlie at the time because he was better-looking. Alan was furious with Charlie and retaliated by stealing Charlie's latest fling, Gabrielle. However, Alan couldn’t quite get even, because Charlie wanted to ditch Gabrielle anyway. Charlie got the last laugh when he slept with Charity again at the end of the episode.