The Awakening is the first book in the Zodiac Academy series. It's marketed as fantasy romance, part of the "bully romance" subgenre. I bought my copy new.
Review:
Darcy and Tory are twin orphans who were raised in various awful foster homes. They were promptly kicked out of their final foster home when they turned 18. The only problem? Their secret savings stash is still in the house. They're able to get their hands on it, but their lives are almost immediately upended by the arrival of Professor Orion, a hot-looking guy who claims they're both Fae, Changelings who were swapped with human twins when they were babies. They have powers linked to the elements and their Zodiac sign, Gemini.
It's a lot to take in, but there's some appeal to going with Professor Orion (plus, he doesn't really give them much of a choice) - if they can graduate from Zodiac Academy, they'll inherit a sizeable inheritance and finally have the freedom and security they've always wanted. They'll also have the chance to reclaim their parents' throne - this, unfortunately, makes them a target of the Celestial Heirs, the young Fae men who've been raised on the understanding that they'll share the task of ruling over Solaria, the land of the Fae, together.
Right from the start, the twins are separated, required to be in different Houses. Although they still share a lot of classes, they're generally surrounded by potential enemies. It's tough to tell who they can trust, and it doesn't help that at least one of the Heirs may be keeping secrets from the others.