Lost Souls Series by Alexa Winters

Ruby Collins was only trying to make it through the day... She certainly hadn't planned on getting abducted by a sinister alien race and forced into a fight-to-the-death match. But defeating the beast is just the beginning of her problems. It turns out she has a soul mate in desperate need of her help. Drake is on the run... Consumed by revenge for so long, he wasn't expecting a soul mate. Can he choose between vengeance and love, or can he find a way to have both?