The Associate - The Associate, #1

Courage counts for everything. Nate Holliday is your average teen, living a fairly ordinary life in Portland, Oregon. Born without a right hand, he copes with his disability the best that he can, although he still feels like an outsider. His fairly ordinary life changes when he meets Ukiko Monaghan, a woman from an alternate Earth. Ukiko, known as Dividing Woman for her ability to split her body into multiple copies of herself, is after a violent criminal named Astral, who can summon up demons from another dimension.
Astral is aided by Tony Lethal, a thug who enjoys stomping people. Together, they are in search of the Spark, an all-powerful weapon, and Ukiko enlists Nate's help in finding it before they do. Now, Nate, along with his girlfriend, Melanie Sarkosian, have to avoid spectral demons, the various branches of the law, and curiosity seekers as they race to find the Spark before Astral does. It's a hard journey, one fraught with danger, and Nate has to conquer his own demons before he can conquer those who seek to defeat him in his quest.
Sometimes, courage is all you need.