Help identifying a book?

I was talking about a book with a friend the other day who can't remember the title or even who wrote it. It was about this kid who lived in a house and there were fairies or something in the house. But they were not nice fairies and one in particular used to come out of the wallpaper and be generally nasty. There was like another world in the walls. She remembered one scene where the "fairy" came out at night (always at night) and he used to go through the fridge and lick everything that was in there. If she remembers right, the kid ended up in the walls and had to get out. She thinks the nasty fairy was his brother of something. Any ideas?