Teenage Mutant Ninja Turtles 2011

(I got the idea from Becky)
You were the turtles' youngest sister, but they mostly ignored you. Only Splinter, your loving father and your brothers, loved you all equally. Then suddenly, one night, you ran away from home. Of course, no one except Splinter noticed you were missing. And when they did, they searched everywhere and lost hope of finding you. After five years of patrolling, a factory exploded. Most importantly, it was Shredder's factory. When they arrived, they saw you with some half-human, half-robot creature. You were laughing together, and that only meant you had turned to the dark side because your brothers weren't giving you the attention you deserved. And when they returned back to the lair, Mikey immediately began to cry on Splinter's kimono, telling him that you turned to the dark side, because your brothers' hearts were broken because they did not give you the attention they deserved, and that you are now a villain with some half-human, half-robot.

Leo: The eldest brother and leader of the team, wears a blue bandana and two katanas.

Raph: Hot-tempered, often regrets what he did, wears a red bandana and a pair of sais

Donnie: The brains of the team, kind and understanding, wears a purple bandana and his bo staff

Mikey: The most irresponsible, sweet and cheerful, wears an orange bandana and a pair of nunchucks

You: A cheerful, beautiful, and vindictive person, wearing a black bandana and a pair of blades

Rob: That half-human, half-robot guy, he's good friends with you, gives you too much attention, and loves to mess with you. He hates the Turtles for how they treated you. It turns out he's Shredder's son, but Shredder abandoned him just like your brothers did to you.