Dennis almost sighed with relief when he thought the stranger, Sebastian, was going to walk past the store. But he didn't. And Dennis silently cursed himself for not moving further back into the store. His curiosity was a thing that was never going to let him do things properly. He couldn't hide himself away well, because he wanted to see if Sebastian was going to find him first. There was a thrill in the curiosity, but not so much in actually being caught.
Still, knowing that he was found, having the stranger stand and block his way out, he tucked himself behind the shelving case even farther (hadn't worked at Fortescues, wasn't going to work here either). Until Sebastian pulled out the letter from McGonagall.
"Do I get to stay there? Or are you going to try and send me away again?"