Sweet darkness up on us all

When two girls were born one was dark and one was light the light sisters name was Opal she was beautiful and sweet the most kindest person alive which made the dark sister evil her sister Marble was born light but once her sister got all the action her shadow formed into a dark lighted character on her and her shadow she was evil and nothing like her sister but, she was beautiful more beautiful than her sister, but why were they born you ask well ever time a creepy pasta character is picked one of these children are born most of the children are chosen up on because there light brother or sister will die,be killed, or I'd Dead. But once Marble is chosen up on she will die and never come back. So what will happen will Opal kill her sister before she is chosen or will Marble kill her sister and become one who is powerful