Nightshade by Andrea Cremer
This was very L.J. Smith (Night World not Vampire Diaries to be specific). Not like it ripped it off, it just had that kind of vibe, in a good way because I LOVE Night World. I did figure out the twist before Calla but there were still plenty of surprises for me along the way. Calla is the female teenage alpha of the Nightshade pack. Ren is the male teenage alpha of the Bane pack. They are "engaged" or mated and have been since they were born which just so happens to be on Halloween. Which is also the day Ren's mother was killed when he was a year old. They are guardians, or wolf shifters, who are supposed to protect the sacred sites, specifically a cave. They answer to their masters, the Keepers. When they get "married" or complete the union, on Halloween, they will form a new pack which will be named after the cave they are supposed to guard. Enter Seamus, or Shea. A human who has a Keeper for an Uncle; who is his only family. They have been instructed to be nice to him and keep him safe. Well, Calla has already met him; she saved him from a bear attack. She and Ren are supposed to be dating but not be intimate. Now she is supposed to be guarding Shea. But she also likes him and she spends time kissing both boys, without either knowing. Enter the Seekers (maybe the Searchers); they are trying to overthrow the Keepers. Shea has a tattoo on his back that he can't see because of some kind of spell; it means he's the scion. The Seekers/Searchers are looking for him. While he and Calla are spending time together they discover this super old book, from his Uncle's personal (locked) library that includes a prophecy. About him. He and Calla decide to go into the cave to see what she is supposed to be guarding and there is an abnormally large spider. She gets bit. The only way to save her is with pack blood but there is no pack around so she turns him into a guardian and he saves her. Now he has to hide the fact that he's changed from the rest of the wolves. There is a woman in the cave and she gives him something that only he can hold. Fast forward to the Halloween. She smells him in the forest while waiting for the union. He is tied up. Turns out he is who she and Ren are supposed to hunt and kill together. She sets him free. They kill an incubus. Ren catches them. She tells him everything. He lets them go and creates a diversion so they can get away. They go back to his Uncle's house to get the book with the prophecy, but they get attacked by all of the paintings and the statues. Then the Seekers/Searchers show up. They grab Shea and take Calla too. She starts waking up to Shea arguing with one of the captors about they promised they wouldn't hurt her. So, was he in on it? That's how it seems. This ending makes me desperate for book 2! I had a hard time because Calla couldn't decide if she wanted to be strong or not; she kept saying she was the alpha and she was the leader and then kept backing down from everyone and everything. But she came around by the end and really had me rooting for her. I cannot wait to find out where this goes!