Soul of the Centaur!

Human?:

I had been born, a human girl. Or that's what it looked like, to the midwife. Now, age seven. This is the age, when the truth revelaled itself to me. Just after I had closed the door, prepared to run to school. I had been late, at the time.

The change instantanious. As I was to take my first running step, something was off. The next moment, I was making a good trot. At the end of the short path out of our garden, I had made it into galop.

Bashing into the school yard in record time. Even found a minute to spare.

Nothing had been out of the ordinary, before I had my breakfast. Not that I knew of. Though the change may have caused the delay?

Only now, at the first step, I soon reverted to the old self. The familiar form.

A girl, walking up the steps, entering the building.