Harry let out a tiny laugh of surprise when he felt Draco's arms around him the moment that the door opened. He hugged Draco back, his arms strong and tightening. Draco wasn't going to go anywhere near Voldemort if he didn't want to, even if he was only Tom Riddle here. Tom Riddle did eventually become Voldemort, and if Draco's fears were true, he now had a chance to redo things from the first time around. He just hugged the other boy in response, relieved that he still had someone around who knew all that he did.
"Stop worrying so much, prat. Isn't that supposed to be my job?" remarked Harry with a smile. "Aren't you going to let me in?" He gave Draco an amused glance, but he understood where the worry was coming from. Harry was worried himself, naturally, quite worried. With everyone popping up again, who's to say who couldn't show up?