The Void - Acktorek

Which would you choose-save your sister or save the world?

Emma Edsel's first priority has always been protecting her blind sister Carla. So when Carla begins to develop science-defying abilities that threaten her life, Emma will stop at nothing to save her. With nowhere else to turn, she seeks help from Mitchell, the new boy at school who seems to know much more about it than he will admit.

After his last mission went horribly awry, Mitchell Banks is relieved to have a simple task: seal a small, accidental portal between Earth and other worlds in the multiverse. He didn't count on his growing feelings for Emma-and the dangerous levels of dimension energy contaminating Carla.

Carla knows the voice in her head is evil. Manipulative. Feeding her with a strange energy she can control. She doesn't know that she is the key to a coming global catastrophe and Mitchell's boss will use any means possible to prevent it...including blackmailing him into murdering her.