[hider=Idea 1]Harry Potter
Basically two friends return for their 6th year at Hogwarts and on the train they run into each other but over the summer they had hit puberty; the girl (hopefully your character) blossoms into a beautifully sexy young woman and the guy (my character) goes from a skinny small man to hitting a growth spurt and unexpectedly bulking up. The guy has had a crush on the girl for a long time but never felt like he had a shot with her and now that he's become hot she views him in a different light (or maybe she's always had a crush on him, your call). They fool around on the train to Hogwarts and it becomes apparent to them they they physically enjoy each other and it becomes a game for them to see how many places they can have sex all over Hogwarts and how much they can fool around with each other and not get caught.

Would be willing to do this as an MxM as well, just originally developed as a MxF.[/hider]