Disclaimer: JKR owns, I play.
"I see you watching him."
Remus turned sharply. Regulus Black was leaning indolently against the nearest shelf, his hair, so like his brother's, falling into his eyes. He smiled, slow and cruel, watching Remus smooth the shock from his features, wrestle his pulse back to normal. "I wouldn't count on him if I were you. He's not … reliable," Regulus said, tilting his head so his eyes gleamed in the dusty sunlight, drawing out the last word, savoring it. It hung in the air for a moment between them, and then he was gone, as quickly and silently as he had come.
Remus turned back to his book and tried not to think of laughing gray eyes, mercurial smiles, black hair that scattered starfire in its wake, bright and cold.
The wolf's nostrils flared as it caught the scent of human flesh. It threw itself forward towards the opening door, caught a glimpse of wide, horrified eyes and a hooked nose before the intruder was yanked back into the dark tunnel and the door slammed shut. Howling rage, the wolf threw itself again and again against the heavy wood, scrabbling, biting, filling the room with the sweet, metallic tang of blood.
There was a whisper of air behind him and Remus stiffened as a warm body draped itself against the back of his chair.
"What did I tell you, werewolf?" Regulus's breath tickled his ear and Remus winced inwardly, the healing gashes that crisscrossed his skin prickling with remembered pain.
"Fuck off," he said shortly, and felt Regulus smile against his neck, felt pale, elegant fingers brush like whispers against his skin, tracing the scars.
"I told you he wasn't reliable," Regulus breathed. "My brother eats hearts for afternoon tea. Would you have him eat yours?"
Remus went very still and Regulus pushed closer, nuzzling upwards into the thick gold-streaked hair, trailing pink tongue, feather-light, along the curve of neck and ear. Remus gave a soft sigh at that and Regulus smiled, triumphant, but then Remus's head jerked sideways, smashing bone against bone, and long fingers caught the younger boy's robes as he stumbled back, eyes wide, blood on his face. Remus twisted his hands into the cloth, dragging Regulus forward, crushing the heat of their bodies together.
"Don't you know it's already gone?" he said, lips close enough to brush Regulus's as he spoke, taste blood. He smiled coldly, bright eyes burning into Regulus's pale ones, and let go, watched as Regulus fell.