Headcanon for human au: 

Amethyst took gymnastics as a child and keeps up with it at the gym where Garnet works, so she’s super flexible and can do stuff liking summersaults easy as pie. She doesn’t look it, though, since she’s thicker, and uses this to her advantage. She constantly surprises people with perfectly executed tricks in dangerous places, like off handrails and stuff. She enjoys watching people’s jaws drop when she basically flips off the stairs when they come inside for the first time