For half a second, Sirius was horrifically unsure of what was going to happen. Then Harry hugged back, and it became apparent that he was not going to shove Sirius away, or curse him out for keeping this from him, or call him a disgusting, horrid poofter. Not that Sirius ever really believed Harry would do any of those things, but a man can have his secret worries.
"I'm sorry, Harry," he said as he squeezed him tightly, apologizing for a lot all at once, so much that this Harry hadn't even technically lived through yet. But it didn't matter. Sirius needed to say it anyway.
He felt more than heard Remus enter the kitchen, felt him watching them. He imagined Remus might be smiling. Merlin knew Sirius was. He had to take a deep, steadying breath when it fully hit him that he truly was here, alive, and in this very room with him were the two people who mattered most in the world. Alive, and whole, and (at least for now) safe.
At Harry's joking words, Sirius couldn't help but let out a barking laugh. "Sorry, Harry," he said again, his tone very different this time, light and teasing. He held his godson out at arms' length and squeezed his shoulders. "I missed you."