Doppelganger Series by Marie Brennan

When a witch is born, a doppelganger is created. For the witch to master her powers, the twin must be killed. But what happens when the doppelganger survives? Mirage, a bounty hunter, lives by her wits and lethal fighting skills. She always gets her mark. But her new mission will take her into the shadowy world of witches, where her strength may not be a match against powerful magic. Miryo is a witch who has just failed her initiation test... moreWhen a witch is born, a doppelganger is created. For the witch to master her powers, the twin must be killed. But what happens when the doppelganger survives? Mirage, a bounty hunter, lives by her wits and lethal fighting skills. She always gets her mark. But her new mission will take her into the shadowy world of witches, where her strength may not be a match against powerful magic. Miryo is a witch who has just failed her initiation test. She now knows that there is someone in the world who looks like her, who is her: Mirage . To control her powers and become a full witch, Miryo has only one choice: to hunt the hunter and destroy her. less

Revolution has come to Starfall.To some, Mirei is a savior. Born from the union of opposing forces, her existence offers a way to heal the division between warrior and witch, and brings powerful new magic into the world.To others, Mirei is an abomination. She overturns the ancient traditions of the witches, threatening their stability and corrupting their magic with an influence that should be destroyed.But even Mirei's power is not enough to prevent a civil war... moreRevolution has come to Starfall.To some, Mirei is a savior. Born from the union of opposing forces, her existence offers a way to heal the division between warrior and witch, and brings powerful new magic into the world.To others, Mirei is an abomination. She overturns the ancient traditions of the witches, threatening their stability and corrupting their magic with an influence that should be destroyed.But even Mirei's power is not enough to prevent a civil war. And while she struggles to reconcile Starfall's opposing factions, a more insidious threat is building within her -- because her newfound magic does not come without a price. less