Remus took a different approach to Harry, as opposed to so many other people. The older man was willing to give Harry his space, because when he did the things that he’d done (such as running off), he obviously showed signs of needing his space. Now, should everyone have just left him alone to be a hermit in London? No. But they hadn’t exactly had the most tact in their efforts to bring him back. And while Harry didn’t know that Remus had been giving him his space (he hadn’t even known that he was going to be here – why didn’t anyone tell him these things?), if he had he would have been appreciative of the gesture.
As it was, Harry hadn’t known that Remus was here, so turning to see his former Professor was more than a surprise to the Boy Who Lived. Harry stared up at him, listened to him say his name and ask the polite, conversation starting question, but didn’t say anything for a minute that would drag on and feel like forever. He finally tensed his jaw, though, and straightened up. The temptation to turn and flee was still there somewhere in the back of his mind, but thankfully he wouldn’t do that. Not with Remus. Not with Lupin.
“Professor.” He’d called him that, even after Lupin had resigned from his position at Hogwarts. It was habit. It was what he’d been to Harry the first time he’d met him. While he thought much more of Remus than simply being his Professor, the title shared some bit of comfort with him. It was familiar, it was old. It was comfortable. “I’ve – well. I’m here.” That was how he had been, Remus. He was in a loony bin.