I've never expected this end. I'd like to read the sequence to this. I'm eager to know how Lily would go to James and how she would have a relationship with him after Sirius let her go. "Bury her feelings", these words create a sensation. How would she get to love James after this? It's very intriguing.
The way you wrote about her beauty and his inner thoughts is impressive. You wrote they got together once and then Sirius let her go, which meant he was loyal to James after all. Sirius in your story showed what he was made of, which keeps lingering in my mind.
You write vaguely sketchy characters so, so well. I'm not quite sure how to feel about Sirius here, which is what makes this so amazing - the numbness he's describing feels so, so real to me, and the coldness with which he's manipulating her really makes my skin crawl. I don't know that that was his original intention - I tend to think it wasn't, but correct me if I'm wrong - but it does become his motivation in a way that's deeply, deeply unnerving, especially since he does end up sleeping with her. It's not difficult to believe of Sirius, though. In the books, he always came across as very single-minded - he was willing to do pretty much anything to get an end that he wanted, and I can see him justifying trampling Lily's feelings to make James happy. It's so disconcerting, but at times, so was canon!Sirius, and I love the way you captured him here. <3
Tiny note - the formatting got a bit messed up in the transfer. Other than that, though, I really really enjoyed this!
I think "vaguely sketchy" is also a great way to describe me so... :P I'm really glad his complicated nature hit a nerve. I do think his motives are slightly less evil than they appear at the end. In my Sirius headcanon he's suffering from guilt/shame about his attraction to Remus and his playboy behavior is to compensate for not coming to terms with being gay. He's also suffering from low self esteem where he just doesn't think he's worth Lily's affection and that causes him to push her away. If he's going to break her heart, he's going to do it in a way that benefits his bff James. One of my many backlog story ideas is to write about Marauder era love stories that would give more background to this.