This is the X-Men Marvel AU!
WriterChan's Marvel AU's include both Belle and Bee Perez!
Belle and Bee are both orphans who somehow stumbled upon a children's labor factory run by an orphanage headmaster who keeps them there. Bee comes down with a terrible cough and Belle works extra to get enough money for medicine. Belle ends up passing out on the concrete ground outside after having to carry around a block of wood for two blocks. She later wakes in a nice room. Belle sees a wardrobe and goes through it, finding a nice dress and putting it on. She goes downstairs and meets a man who introduces himself as Charles Xavier. He asks if she's hungry and she soon finds out that he could read her mind as he instantly discusses how painful it must be to have been the bigger sister. Charles later drives to the orphanage and grabs Bee. Charles adopts both of the twins and helps them become X-Men. Later he decides they need a real family but soon find them back home, Bee's arms and legs are broken and Belle is carrying her on her shoulders, Charles frantically takes Bee to get taken care of and Belle states this wasn't the first time in the period of them being back at the orphanage. Charles decides than and there to raise the girls as his own and dismisses the orphanage requests to send the twins back.
Belle- She is able to use her hair as weapons against her enemies. Her costume is mostly dark pink and her hair is Black with white streaks.
Bee- Bee has the same powers except her costume is a dark purple while her hair is black with purple streaks.