How This Led To That

We know how it started, and we now how it ended. We know that Lily was there for Remus, and that Sirius remembered her eyes. We know that Lily and James went from being enemies to lovers. And we know that Peter betrayed them all. But how did it all come about? We don't know for sure. But maybe it went something like this... [Lily/James, Lily/Marauders]