Entice (Need #3) by Carrie Jones

Zara and Nick are soul mates, meant to be together for ever. But that's not quite how things have worked out. For starters, Nick has gone. He has been taken to the mythical place for warriors known as Valhalla. Zara and her friends might be able to get him back, it's just not going to be easy.

Meanwhile a group of evil pixies is devastating Bedford, with more teens going missing every day. An all-out war seems imminent, and the good guys need all the warriors they can find. But even if Zara and her friends do discover the route to Valhalla, there's that other small problem: Zara's been pixie kissed. When she finds Nick, will he even want to go with her? Especially since she hasn't turned into just any pixie... She's Astley's queen.