Waking Gods (Themis Files #2)

...Humankind faces a nightmare invasion scenario made real, as more colossal machines touch down across the globe. But Rose and her team at the Earth Defense Corps refuse to surrender. They can turn the tide if they can unlock the last secrets of an advanced alien technology. The greatest weapon humanity wields is knowledge in a do-or-die battle to inherit the Earth . . . and maybe even the stars.

And I Darken (The Conqueror’s Saga #1)

No one expects a princess to be brutal. And Lada Dragwlya likes it that way. Ever since she and her gentle younger brother, Radu, were wrenched from their homeland of Wallachia and abandoned by their father to be raised in the Ottoman courts, Lada has known that being ruthless is the key to survival. She and Radu are doomed to act as pawns in a vicious game, an unseen sword hovering over their every move. For the lineage that makes them special also makes them targets.