Regulus had done his best. He really, truly had. He'd tried to save Sirius from getting tortured at Bellatrix's hands but he'd just made it worse, in the end. He'd tried to keep his brother coherent too, but Bellatrix had made sure to give Sirius a concussion before they had to leave. A bad one. The sound his head makes is sickening.

He's shaking. Bellatrix leaves first but he doesn't have the time to do anything constructive. He flicks his wand to cast the strongest numbing charm he knows on Sirius to dull the pain, whispers an "I'm sorry," and leaves.

(Cruciatus, Imperius, broken bones, a concussion.)

He finds out that Sirius is in St. Mungo's later and he'd known it would be that way but his heart sinks anyway. He waits until he can get away without fear of being caught and sneaks-bribes-slithers to his brother's room, barely even breathing as he pushes open the door carefully. He just wants to check. He needs to see he's alive. Needs to know he's going to be (physically) all right.

He needs a lot of things.