*CROSSPOSTED FROM AO3* It was nearing the end of his fifth year at Hogwarts, and Regulus Black was getting on with it. Things at home had been far from perfect since Sirius ran away and left him behind, but that didn't mean that he'd stopped caring about his brother altogether. He just wasn't willing to admit that to Sirius. So when Regulus is woken one night by an infuriated Severus Snape, he doesn't want to get involved with whatever his brother's latest 'prank' is. But seeing him isolated from his friends in the following days, and worried about what the coming summer will bring, Regulus decides that he has no option but to get involved. He couldn't possibly be aware of what would happen when he pushes himself into the orbit of one James Potter. With the threat of war looming and Potter busy chasing that muggleborn girl, what could possibly pass between him and Regulus that would compromise the Slytherin?