21 used to be a woman out to eat everyone in the world to increase her power, but was also a kind hearted woman who care for others as well.
Soon, she would split herself in 2 with a Good 21 and a Evil 21 remaining. After spliting with herself and fighting her evil half alongide Goku and the Z Warriors, 21 decided to make the ultimate sacrifice and kill her along with her evil version vi the Super Spirit Bomb.
Or did she?
After takling her evil self, she saw a light around her before closing her eyes about to take a hit, but when she opens the back up, she finds is alive, and transported far away from Goku and his gang.
Maybe this could be 21's chance at a second good life, assuming she can keep her hunger down.
Android 21 is a calm, soft hearted, smart woman who loves sweets, though she can get a little, too hungry for food at times.
She also has the ability to transform, giving her stronger fghting capacity and the ability steal moves from people and to turn anything or anyone into food. She tries not to use it n innocents, but a uncontrollable urge may make her use it someday.
21 just loves eating, especially sweets, and her String Cheese.
Usually 21 doesnt want to eat others (though she wont complian if they offen them to her to satify her hunger) but her hunger can be a great force.
Her transformed state
She can eat a alot in this form, though since she isnt fully majin, the fat stays.