It’s an undead baby dragon, produced by a failed magical spell. It probably would be cute if it weren’t partially decayed.

Young dragons are relatively defenseless. They are born with relatively soft scales, which are shed and replaced with harder ones as the hatchling matures. Once a hatchling’s wings grow in, it typically marks the beginning of maturation. At this point they are often capable of hunting on their own and are usually left alone by their mother.

Halloween is a strange and powerful night. Nina's orphans had crept out. Fear began to root; the scent of dragon-blood blew on the wind. Most wanted to flee, but Leukos was inexorably drawn to the stench. The source was a maimed hatchling. "I want-" it gasped, "Want-" Its life bled out. Leukos collapsed, his own magic drawn into the corpse. But white magic cannot revive the dead. Quite. Leukos woke. He and this thing were in Albus's den. For his part in the creature's unlife, Albus charged Leukos with its care. Leukos only said, "He isn't an 'it,' he's 'Wants.'"