Can domone explain yhe dark secret?

The dark secret is that when they were little kids, one stormy night, when seme's mom and dad had locked them in the black room. They wished that the parents would disappear leaving them alone. And their wish came true, their malicious wish got too dark and took a physical from inside the mirrors. Then the hands came out of the mirrors to the real world and killed the parents. After that their malicious form lived in the mirrors and seme learnt how to use the power but uke lost his memory so didn't know the whole truth until the end.