Remus was tired. He hadn't slept well since Sirius's death, and now he had to adjust to this new place. And even without those difficulties, where everything felt wrong, all the new information that had been forced on him was more than a little overwhelming. And, to top it all off, Sirius was back from the dead. It wasn't that he wasn't glad to have the other man back, he just didn't know how to process it. He didn't know whether to kiss Sirius or punch him, and he still wasn't quite sure which one he had settled on when he heard the knock to the door.
He'd made tea, which had helped to calm him down somewhat, but he was still a mess of nerves. He closed his eyes and took a deep breath to steady himself, then opened the door. He didn't know what he had expected, but seeing Sirius standing there was almost enough to shatter what little composure he'd managed to retain. "Oh god," he said softly, just staring at the other man, "it's really...I mean...you're..."
He hugged Sirius, not unlike the time in the Shrieking Shack when he'd learned of his lover's innocence, his shoulders shaking as he buried his face in the other man's shoulder and finally broke down. "Never again, Sirius," he whispered. "Don't ever leave me like that again."