I´m sorry I don´t remember much but what I remember was that Sam and Cas are friends and Dean is the annoying big brother. I think maybe Dean has a crush on Cas but Cas has a crush on Sam. They go to a carnival or an amusement park or something like that and Cas gets shown his future and it´s with Dean and not Sam. But then he realises that what he and Dean have in the future is pretty great. It has a happy ending. If anyone could help that would be great! Also sorry for bad english, not my first language :)