“What are you doing lurking in the corridors late at night, Potter?” a voice spat from behind Sirius. He muttered a spell and his wand lit up as he turned around to face the boy. Regulus. Sirius looked around for James. He wasn’t there.
“What are you on about, Reg?” Sirius tilted his head at his younger brother— at his ironed robes and sharp eyes. Regulus’ face was set into a sneer. He looked so like their mother in that moment that Sirius took a step back.
“That’s what it is now, isn’t it? You’ve left home and now you’re a Potter?” Sirius flinched. Regulus hating him, he couldn’t understand it. But he didn’t like it. He didn’t want it. Regulus lifted his wand to Sirius, but not like it was a weapon. He lifted it instead like it was an accusation. “You ran from there, Sirius. You ran from her. Like a coward,” Regulus spat.
“Reg? What is—what do you mean?” He blurted. Regulus wasn’t like this. He wasn’t mean and bitter. He wasn’t like them. But maybe he was now. Maybe it was Sirius’ fault those steel grey eyes that used to mirror his now mirrored his mother’s hate. Maybe it was Sirius’ fault Regulus’ wand was stretched toward him, threatening to reopen every wound and bruise and scar. Maybe it was Sirius’ fault Regulus hated him.
“You ran from her, Sirius,” he drawled, stepping closer. Sirius stepped back until he could feel the cold stone against his back and one of the portraits muttered something over his shoulder. Regulus didn’t speak again until he’d reached Sirius, until he’d lifted his wand up to Sirius’ neck and bared his teeth. Sirius’ wand was in his left hand but he couldn’t do anything. He couldn’t move. So he looked into his little brother’s eyes, his face illuminated by the wand light, and venom coating his gaze. “But you can’t run from me!” Regulus yelled, so loudly that Sirius clenched his eyes shut and flinched. Reg muttered something else— a curse, Sirius realised— and turned, walking away without a single glance behind him. Sirius watched him walk, hoping he’d turn, hoping he’d come back and laugh it off, tell him it was a prank. But Regulus disappeared around a far away corner, only his footsteps echoing through the castle to prove he’d been there at all.
A warm spot grew on Sirius’ stomach and only then did he look down. The pain kicked in like it was charmed only to hurt when Sirius glanced at it. A crimson stain spread over his shirt. It didn’t slow, it didn’t stop. An ache spread with it, crushing Sirius, burning Sirius, freezing Sirius. He fell to the ground, knees up to his stomach and let the pain take over. His spine burned while his blood froze and everything was tightening, closing in and Sirius fell to the floor. He couldn’t hold himself up. He couldn’t think beyond the pain in his stomach. He didn’t even know what spell it was. But he knew where Regulus had learned it.
Sirius watched the far away corner that Regulus had walked behind and listened for the footsteps, listened for Reg coming back with help, with regret, with a smile.
Sirius hadn’t seen Regulus smile in so long.
He watched the empty corridor until he couldn’t hear anything, until everything faded from view. No footsteps echoed through the castle, no one came to help him. Regulus didn’t even care to watch as Sirius’ view faded to black.