Black Onyx by Nikita Parmenter

The fae realm is notoriously dangerous, whereas most supernaturals don’t get thrown into the more dangerous side of fae life until they’re twenty-five thanks to her tyrant father, Farren’s been dealing with it since she was sixteen, brutally trained and punished; she knows her way around a blade.
Thanks to an incident that she very nearly didn’t survive, reprieve comes in the form of Black Onyx academy, which is used to train warriors and enforcers; it should be the break from her father that she needs.
Of course, life is never that simple put into a fated team that thinks she’s nothing more than a spoiled princess who got in using daddy’s money. She’s underestimated at every turn. Throw in assassination attempts, moody shadow casters, a blast from the past that has surprising connections and confusing feelings for her teammates, and nothing is as it appears. Life’s about to get a whole lot more complicated.