She wasn't just idly sleeping next to her witch-in-training master, Leeny was paying close attention to all the lessons and trying all the tricks herself ever since she was a kitten. She has gotten pretty good at her witchcraft despite not having thumbs. The bright spots on Leeny's face, tail, and back are all magical runoff from spells gone awry. She thinks they make her pretty cool, and thought her witch loved her for the bright fur patterns as well. When it was time for Leeny's witch to go to witch academy, Leeny was heartbroken to find she'd been left behind so that her master could get a new black kitten to fit in with the normal witchy crowd.  Heartbroken and bitter, Leeny gave up wanting to be a Witch's Cat, and ran away from home to live her own life and master her skills Human magic was just her stepping stone to a cat's true potential!
The bitterness, though, has never been undone.