Once Maddi ate the fruit she was granted powers. Yes powers. Not one, but four. The first one was to shape-shift. She could transform into any animal. The second one was to heal. Maddi could heal almost any injury or sickness, but not death. The third power was to fly, so she could be as free as the clouds. And the fourth one was the most powerful. It was to copy. She then had the ability to copy moves, voices, even other devil fruits.
These powers that had been granted to Maddi also had a downside. Unlike the other cursed fruits Maddi could still swim, but an even worse curse had engulfed her. Every night for the rest of her life she would have to have nightmares that would destroy her if she didn't wake up. Also she had to make a goal, which we shall see later, that she must finish in order for her to be rid of th nightmares.
Aside from the nightmares, since she was part animal she must mate for life. And she can have only one child (when she's older).
Once Maddi ate that cursed fruit her personallities were split. The Evil Maddi now gaurds One Piece and the Happy Maddi lives in her "happy place". Even with these awesome powers she can't control them all at once, there are three orbs she must collect. The weak one, red, the semi-strong one, blue, and the Super-Nova, Gold. She collected the first and second, but the Gold one will be revealed at Raftel.
Since Maddi was two she was adopted by Arlong the Fishman Pirate, but since Luffy killed him she's been a fisherman on his crew.
If you have any questions please contact me. She sort of has a fun-loving personality like Luffy but also can get serious. And she hates to be teased. She can act stupid a lot but it's not her fault, when she was two Hachi dropped her on her head.
This is sort of what she looks like:
