Details from what I can remember:
So this story was one of those that the OC was taken from our world and put into Doctor Who. The beginning was set it Lake Silencio, which either the person i believe was swimming in a lake in our world and suddenly got thrown in DW. The Doctor and River greets her when she gets out like they're old friends, whenever it gets the time for the doctor to get shot, i think he kissed her (the OC). Whenever Amy, Rory, River, and her meet The Doctor again, he doesn't know her, at all. And the story went on from there and i know that it wasn't a fic where she would go through his timeline, she stays with 11! If y'all know/find any fanfics where it happens like or close to this, please let me know! Thanks for helping me!