I *love* that last line.
After all the vacillations that James goes through, with the "I've got what I want, but I want what I shouldn't have", and "why are you better with him than you were with me", and "I know you and she got together, but I'm not going to mention anything to either of you because this will spoil my moment"... James knows his future. He sees his path forward and he knows what's ultimately going to happen and there's a small (or not so small) part of him that relishes in the fact that he won. He won because he got the girl. Maybe he won because he got the girl and Sirius didn't. Maybe he won because that "other" relationship that Sirius has with Remus, or whatever happened/could happen/might happen between James and Sirius won't be as fulfilling as whatever James has with Lily.
And he calls her "the girl", like she's some prize to be obtained, some kind of destination that he's finally reached and unable to fully process in his "moment of kind of, but not actual" clarity.
He's arrogant and conflicted and "irritated" about the whole thing. I assume that maybe part of his irritation came from his speculation about whether Sirius got there before him, but that's another thing I adore about this style: the reader is left to fill in the pieces with so many, many possibilities and it works, whether it was what you intended for the backstory or not. I just love the way you used this challenge to explore that. I think your raw, stream-of-consciousness style was excellent for exploring this convoluted, twisted niggling of a plot thread. And no, James will *never* say any of that to Sirius' face. :P
Author's Response: Hey!
The strange thing about James is how clear-cut his life seems to be in canon. Like, you know, he's from a respectable-but-not-Dark Pureblood family, he knows he's going to get with Lily since at the latest fifth year, he never seems to have any moral or emotional ambiguity at all ever. Which is weird, because his friends are full of all of that kind of contradiction and the like. So I had a go at fixing that by shipping Sirius with everybody, because that's how I roll... I'm glad you picked up on James' vacillations, is what I'm trying to say.
Lily is, here, absolutely a prize to be won in a competition whose only competitor is James. She ends up a bit like furniture in this one-shot, actually. :S
I think the thing about backstory is just me being lazy (or strapped for time), to be honest. :P
But anyway - thank you so much for your lovely review, sorry about this terrible and late response, etc. :)