No Ordinary Hero — Dee J. Stone

The world is set to explode in three months. The source: a lonely girl with an extreme superpower fueled by the negative emotions inside her. The solution: send fourteen year old superhero-in-training Kale Zenith to be her friend and give her a reason to smile. The problem? The girl trusts no one. With the fate of the world in Kale's hands, quitting is not an option. Perseverance is key to knocking down the many walls around her, and soon he gets to know Lindsay as more than just the girl who will destroy the planet. But there's trouble back home. A secret plot is brewing inside his superhero League, and it's up to Kale to expose the traitor. But that takes time away from Lindsay when she needs him most. Can he save her and the world before it's too late?