Amber

Amber

Close to the end of the series, it is discovered that she has these powers due to an experimental treatment that was performed on a girl who died on the island named Midge, who is revealed to be the narrator of the series. Following the experimental treatment, the "Amber personality emerged" and had the powers to control the island and the people on it. At the end of the series, she is forcibly injected with another experimental drug that is meant to kill off the Amber personality and bring back the "good" Midge personality, but it simply separates the two girls into different bodies, and both of them are angry, with Midge seeming not quite as innocent and good as she was assumed to be.