Oh, wow, wonderful, compelling storytelling. I found myself wholly sucked into this one and enjoying the ride. The back-and-forth structure works incredibly well as the story unfolds.
Charlie's voice is fabulous, but I love your characterization of Remus here, and how much we can tell about him simply through Charlie's observations and recollections.
For a beat or two, Remus didn't move. Then he grabbed Charlie, pulling him to him, his mouth descending on Charlie's, fierce and biting.
Remus has never been strong on the willpower, particularly when it comes to the desires of others, has he? Yet in the end, when he finally gives in to Charlie, it's what he truly wants for himself. And that's the beauty of this fic. Heh.