Somewhere along Sebastian and Ciel's misadventures, they'd picked up a young demon. You.

Sensing your worth as an ally, albeit an odd one, Ciel took you in and made Sebastian your mentor. Great! He'd teach you how to master your powers as a demon, and in the process, he'd see his goal of turning you into a tool to protect the young master come to fruition.

One of a demon's many abilities was to turn into anything, and become anyone. It was certainly a useful skill for you to have, since Sebastian's status as a butler often prevented him from being able to. It just wasn't in his best interest. But you?

So! Today's lesson: transformation. Sebastian watched on as you tried to make use of your power, turning into anything but what he'd asked. "Pitiful." He sighed, mostly to himself, but you heard him. "Why don't we start off with something... Smaller? Perhaps a bird, or a cat." A cat? Was he just doing this for his own entertainment?