Belle decided to start with her brother. He seemed to be the most afraid and watching him squirm wasn't nearly as fun as with her younger sister, so Belle wanted to end his misery quickly.
"Congratulation brother. You'll be a great heroine!", Belle said to him.
"Why do I have to be a girl? Can I not just become a normal superhero?", he asked.
"You'll understand soon", Belle reassured him. Then she hit him with her eyebeams.
The clothes of her brother transformed into a skintight green suit that covered everything underneath his head, but left nothing left to the imagination. Then her brother startet to grow up, but his penis got smaller and disappeared. Her brother visibly orgasmed from this and Belle almost orgasmed from watching it. Then her boobs, ass and muscles changed, until they were very similar to Belles. When the transformation was complete, she kissed Belle.
"Wow! That was like an explosion of good feelings inside my body! Thanks Belle!", the new heroine said, after she was done with the kiss.
"You're welcome. Do you understand now?" asked Belle.
"I'm starting too. When I look at you or your twin sister or even my own new body... I feel good and I feel like the explosion could come back. I love it, to have this pretty explosion-making body!"
"Give me my Sons back!", their mother screamed.
"But they're so much cooler now, mom", their youngest sister said.
"And sexier!", Belles twin sister said.
"This has to be a nightmare", said the snitch.
Belle and her new supersister ignored them.
"What will be your name now?", asked Belle.
Her new supersister glowed and formed rings and other construct out of light.
"I feel light inside of me and like I can do everything with it. So I'll just be Light now!", said Light.