In the Shadows. Realm Walker, #1

Terra is a testy 17-year-old thrown into a secret world and told she is to act and look like an elf. She has no plans to do anything but be a teen, fall in love, suffer heartbreak, pick herself up, and get the most out of her senior year. When her father dies, none of that is an option. She has to leave her home and best friend to live with an aunt she's never heard of. Clyde, her ferret, is all she has left of a life she once lived as she learns to manipulate whoever she can and plunge into her new reality - feet first.
Crazy gets insane when Terra unknowingly walks into Drakonia, the realm of vampires, and saves a young human woman - Tania - from the grasp of Blood River.  Bringing her across the curtain between realms, she puts both their lives in jeopardy. On her mission to find a way home for Tania, she learns she is more than was presented to her as she has the ability to travel to other realms. The only explanation is that she is a hybrid, giving her magical abilities different than others.
She keeps this secret as it may cause her more distress, and keeping Tania hidden is already a challenge. She must find a way to get Tania home safely without getting killed or banished. Which means challenging the Tribunal and giving away the secret that she is not elfin.