Biderdoo Harpell is one of the wizards of the famed Harpell Family. When a transformation potion went wrong, Biderdoo accidentally changed into a dog. None of the wizrds could figure out how to change him back, so he stayed as the family dog. When The Time of Troubles came around, the magic wore off, and Biderdoo became human again. He worked frantically until he found a potion that could change him back, but he was left with part of the dog gene. Therefore, he can change into a werewolf at will. Helped defeat Uthegental after Puddlejumper, his half-frog, half-horse, ride had gone from his side when it got hit by drow magic. Not much for fighting, but still managed to kill a kobold with his teeth by biting his throat out. Bit Uthegental in the back of the neck as a werewolf until he bit through his spine, severing the spinal cord, and ending the large drow's life.