Remus was willing to give Harry his space mostly because Remus had been there. Who was the one who'd turned and ran when he'd lost everything after the first war? Who was the one who'd pushed so hard he'd driven everyone away again this go round? He certainly couldn't fault Harry for doing exactly the same thing he himself had done, could he? Sure, he'd have shown up on the young man's doorstep at some point or another, if for no other reason than just to say hi. But opportunity was presenting itself and who was he to argue?
Harry's posture was defensive. Remus recognised it, knew it, and embraced it in himself. Again, why would he fault Harry for doing something he himself had done a thousand times or more? It was sad that here he was at this facility to help others when sometimes he wondered if he didn't need it just as much as they did. But then Harry called him 'professor', just as he'd done all those years ago, and the older man relaxed despite himself. He wasn't going to be turned away. Not yet, at least.
"So you are," he said with a small smile. In truth, he wanted to embrace the young man; he wanted to give James and Lily's son whatever comfort he possibly could. He wanted to at least squeeze his shoulder and reassure him that he wasn't alone, not here. But he couldn't. There was only so much contact the boy would allow, and Remus knew better than to push his limits right away. "But that doesn't tell me how you are. Just where you're living." Because crazy, after all, was simply a state of mind, especially when your own mind was controlled for you once a month.