In the dead of night, a powerful spirit drifted through the air, searching for someone to amuse it. This spirit was not malicious, not in the slightest, but it was certainly mischievous. On this night it was in the mood for some transformation, but it was not looking to be the one to do the work. No, this spirit was looking to imbue someone with a power of transformation, someone they could observe as they wielded this power.
The person with the powers is able to change the physical and metal traits of any person, including body parts, clothes, personality traits, age, etc. The user can even use the powers to alter their own physical and metal traits as well. The sky is pretty much the limit, although the powers don't work on inanimate objects, and might make weird things happen when used on animals. However that does not mean people can't be given traits belonging to animals or plants or inanimate objects or even fully transformed into one of those things. If a person is transformed entirely into something that isn't a person, don't fear, they can still be transformed back no matter what happens. The user of the powers can also control if people are aware of any changes. The default is to make people unaware of the changes unless willed otherwise. All the person with the powers has to do is think about a change and it will occur.
The spirit didn't just want to pick anyone, though. It was looking for a particular kind of person. While this spirit was certainly mischievous, it was also benevolent. It was looking for someone who desired a change, someone who's life it could improve by granting them with a power. And so, in the dead of night, the spirit felt itself drawn to someone wishing for change. it could sense the desire, and was drawn to it.