He'd thought he was beyond feeling any more pain, but each of Regulus' words hits him like a blow. He takes every one of them in turn, though, head bowed and shoulders hunched, hands balled into fists on the floor, because he deserves them. He's the reason that Regulus is at this point, and anything that happens from here on, he's entirely to blame.

He's crying a bit more noticeably now, the silent tears having turned to soft gasps verging on actual sobs and he knows he's about to lose it. It's the flashes of bright color from the spells over Sirius' bed that spur him into movement, and he pushes himself to his feet, reaching out blindly for the wall to steady himself.

"I should... go. Find a–" His throat feels thick, and he can barely get the words out as he stumbles toward the door. "–Healer." He's very nearly through it when he pauses, head still hung so that his hair falls over his eyes and unable to look at Sirius or Regulus. His last words come as a barely audible whisper before he bolts from the room:

"I'm sorry, Reg."