is
here This one burned to write. I had to bribe myself with the promise of homemade popcorn, a large glass of wine and an episode of Merlin to finish it (all of which were very good - I watched The Mark of Nimueh which I haven't seen for ages. I'd forgotten that Morgana is made of awesome in this episode. I love the fact that she uses a 'real men would...' line on Arthur and it actually works. *hearts*)
I'd thrown in some comments from James right at the start of the story when they were in the lake, and I thought at the time that James probably did know that Sirius was gay and wasn't comfortable with it. I also knew that the others' reaction to Dumbledore and Grindelwald would probably provoke an outburst from Sirius. Together with the generally obnoxious behaviour James has shown over the last few chapters, that came together to this. I wanted to make it very clear that even Remus is struggling to follow the twists of this fight, because he doesn't think like they do. James and Sirius understand each other like lightning most of the time and they think in similar ways. This is what happens when they turn that on each other, and it was meant to be nasty.
Of course, this is a Sirius who has just been locked up by his family for weeks, desperate to get back control over his life, and a James who is as much a product of privilege, wizarding and otherwise, as any boy can be. This is the point where their hive-brain suddenly hits the profound differences between them and the key difference is how much more isolated from wizarding culture Sirius has just become.
On top of that, James has obviously seen Sirius' feelings for Remus (it's not like Sirius has been subtle). He doesn't trust the suddenness of this attraction, and he is also capable at looking at them and seeing one needy, abandoned, ruthless boy and another who will do anything for those he loves. It's a relationship which has the potential to be deeply fucked up (and we know that it was by 1981) and James doesn't want them to get hurt.
So he behaves like a complete arse whilst being utterly confident he's doing the right thing.
The main technical difficulty in writing this was varying the swear words. I work with teenage boys (it does wonders for my vocabulary) and know perfectly well that in a real fight like this every other word would be 'fuck.' Unluckily, that doesn't work on the page.
Hmm, now to bed, or another glass of wine and The Poisoned Chalice?