It almost looks like Regulus is going to cry but instead he buries his face in Sirius' neck with something that sounds terribly like a sob but evens out into a shaking breath.

"Please," he whispers, "Let's never be apart like that again. I thought, because you avoided me--" that Sirius had hated him. "It was stupid. Things will be okay now."

He'll get out, somehow. And hope that Sirius really is okay.