Regulus should have expected this. All of it. He considers casting a belated silencing spell on the door at least but it's too late anyway, so instead he just hurries up his timeline, each cry making him feel like he's being stabbed in the heart repeatedly.

And of course Sirius is still asleep; he steps close to the bed and places a gentle hand on top of his brother's, glancing to the door furtively just in case. "Wake up, gēge. I need to go, but I want to talk to you first."

He hopes he doesn't have to do much more to wake him.