Midnight is not that good at flying, though she is better at it than Tabby. In fact, she started in about the same place as Tabby stayed at throughout the series. Like most cats, she is put to shame by Ethel Hallow's cat Nightstar. Midnight is described as a normal, easygoing black cat.
In The Owl and the Pussycat, Midnight starts fading away due to losing his magic. Mr Rowan-Webb says that familiars lose their magic when their owners’ magic becomes corrupt, but it turns out that Midnight is a mother (and therefore a she)! Miss Drill explains that when mother cats have kittens, they transfer their magic to the kittens, leaving the mother low on magic. When Maud says that Mr Rowan-Webb told her that familiars lose their magic when their owners’ magic becomes corrupt, Miss Drill says not to listen to wizards for advice about witches’ familiars.