Regulus moved behind Sirius, watching his brother. He hadn't expected Sirius to see it, at least not for a while, but he would not turn his back on Sirius or Andromeda, and this was his way to show the world.
He put a hand on Sirius' shoulder and squeezed gently. "I haven't done anything. You are my brother, even if you are a prick," he added wish a grin, because there'd been too much seriousness for a day and he wasn't sure that either one of them was ready for that. "We move forward, Sirius. Our parents aren't here to tell us what to do. As long as you want, it's here for the taking. And now would you like some tea? We can be civilized and shock Kreacher. He'll have something to tell Mother at night."