Oh, this is utterly creepy -- really, as any story about Umbridge should be. The vivid detail of that poor kitten and the origin of that awful cat plate collection is just shudder-inducing. I do love how deliberate Umbridge is here, how perfectly in order and in control, just as she is in canon. This in particular:

An iced biscuit, perhaps? Not yet, she told herself. It was so easy for a witch alone to let herself go and slip into indiscipline. An iced biscuit when the letter had been sent, but not before.

This is so perfectly Umbridge.