red string of fate au where james is sick and tired™ of having to wait for destiny to bring his soulmate to him.
especially because in this universe the intensity of the red in your string shows if you are close to your other half (bright red when you are really close, but a maroon-ish color when far)
also, only you can see your own string, and the only part that's truly visible is what's tied on your pinky finger and a bit of the loose part, but it's just a couple inches of it that then turns invisible so it's not a bother.
so! james' string is bright bright red, like BRIGHT red. his soulmate is close but he has no way to find out who it is until "the right moment" which is when he and his soulmate get to hold hands for the first time.
james tried to hold hands with EVERYONE (who was willing and with a bright string as well, he's not daft) on the gryffindor tower, his quidditch team, and even some students from other houses who he has classes with.
he gets so riled up and impatient, that one day he just snaps.
which means: he goes to the great hall for breakfast (because everyone is there), sits at the very beginning of the gryffindor table (to have everyone in his field of vision), grabs as much of his red string as he can (so, right before it becomes invisible) and. pulls. like. a. motherfucker.
two things happen in like two seconds.
one. regulus black, who was just about to leave the great hall, is yanked backwards and barely caught by barty before he hits the ground. his arm painfully stretched to james' direction.
two. before james can finish processing that what the fuck, regulus black is his soulmate and sirius is going to murder him. regulus manages to stand back up properly, stares at his pinky like it has personally offended him, and. also. pulls. like. a. motherfucker.
so james also gets yanked, only that, as he was still stunned from what just happened, he gets pulled out of his seat and dragged for maybe five steps towards regulus. arm painfully stretched towards him.
sirius, who has been watching everything, loses his shit.