Mrs. Arabella Figg, Harry's neighbor on Privet Drive, is the woman with whom the Dursley's leave Harry if they are going someplace nice or fun. Harry doesn't know that she is a Squib, a magical person who cannot do magic (not a muggle!) and that she's working for Dumbledore, to keep a lookout for Harry's welfare. After Harry and his cousin Dudley are attacked by Dementors, he uses a spell to make them go away, and Mrs. Figg is a witness. Good thing, because Harry is brought up on charges for "underage wizardry," and she is called as a witness for the defense. Here, she is describing the Dementors and the feeling they created ... "as if all the joy had gone from the world."