Riders of Paradesos Series by Wendy Knight

Working with the ex you secretly love to save the souls of the innocent is almost as bad as working with a mighty battle unicorn who would be thrilled to watch you plummet to your death. Scout is used to pain. Her body has been broken, her heart has been broken, and the only thing keeping her together is her relationship with her younger sister. Lil Bit believes in unicorns and terrifying monsters she calls soul stealers. But unicorns and monsters aren't real.. moreWorking with the ex you secretly love to save the souls of the innocent is almost as bad as working with a mighty battle unicorn who would be thrilled to watch you plummet to your death. Scout is used to pain. Her body has been broken, her heart has been broken, and the only thing keeping her together is her relationship with her younger sister. Lil Bit believes in unicorns and terrifying monsters she calls soul stealers. But unicorns and monsters aren't real...are they? When Lil Bit falls prey to the mysterious disease sweeping the country, Scout has two options - believe the doctors who say it's a pandemic or believe Lil Bit, who says it's the soul stealers. She chooses her sister and goes looking for the unicorns who are supposed to save them. What she finds aren't the cute pastel mythical creatures she expects. Battle unicorns are big and tough and full of attitude. Who knew? Unicorns are real and so are the monsters. Soul stealers are reaping the souls of the innocent, and the unicorns are fighting to stop them. But to save the world, they need the help of humans - the enemy they're dying to protect. And first to sign up for the fight is the ex-boyfriend Scout's heart won't stop loving, no matter how determined she is to hate him. less

Fighting alongside the boy you shouldn't love is hard enough. Doing it while riding a unicorn who would gleefully fly to her death with you on her back is worse. What makes it insane? Doing it in hell. Scout and her unicorn, Ashra, risked everything just to make it into Aptavaras. Their plan is to free Scout's family and the stolen souls, and seek vengeance on the man who took everything Ashra had once lived for. What they hadn't counted on was Trey and his unicorn, Torz, following them... moreFighting alongside the boy you shouldn't love is hard enough. Doing it while riding a unicorn who would gleefully fly to her death with you on her back is worse. What makes it insane? Doing it in hell. Scout and her unicorn, Ashra, risked everything just to make it into Aptavaras. Their plan is to free Scout's family and the stolen souls, and seek vengeance on the man who took everything Ashra had once lived for. What they hadn't counted on was Trey and his unicorn, Torz, following them. It might be the only thing that will save them. Because in Aptavaras, the soul stealers are many and the chances of survival are slim. Even if they can get past the demons, trick the demon master, rescue the souls and escape with their lives, there's only one person who can open the gate, and he's on the outside defend-ing the world. But Scout, Trey, Ashra and Torz have one thing the soul stealers don't- A reason to live. less