This is just an all-around fantastic little bit of non-con and Snape/Marauder angst. I love that it's really not about Snape at all. It's about the relationship that James and Sirius have with each other; Snape's just a convenient prop that they can use to reaffirm their own bond. The little moments when James almost sees Snape's humanity are wonderful. And your ending -- classic! LOL