Sapphire Arrow (Worlds Colliding Arrow, Book One)

Jill Wright and her sister Amy lost their parents and their brother to a shootout in Mexico six years ago. The trauma led them to a boat ride in the middle of the ocean that was shipwrecked, leading to Amy's disappearance at sea and Jill being stranded on Lian Yu for six years. She comes to Starling City with Oliver to start their mission of cleansing the city of evil and criminals, becoming vigilantes.
Justin Smoak is a bodyguard hired by Moira to protect Jill after she and Oliver are attacked after they come home. He's ex-military and a self-defense class instructor. Once he finds out the truth about Oliver and Jill, he becomes set to the mission along with John, and goes to his sister Felicity for help from case to case.
Skylar Queen is Thea and Oliver's little sister. She was devastated and angry when her brother and father disappeared at sea five years ago. But instead of diving into drugs and alcohol like Thea had done, she divulged herself into taking self-defense to take out her anger, where she met and became very close to Justin.
Jessica Lance is the middle sister to Sara and Laurel. Like her father, she's a detective for the Starling City Police Department, while Laurel is a district attorney. She does not hate the vigilantes, but she's not too fond of them, either. That is until she needs their help solving a case involving her one-time boyfriend, and they help her stop the culprit. But will working with the vigilantes without knowing their identities cost her her job?
Twins Kira and Karma Mahageni are members of the Chinese Triad, only because they owe their lives to China White, because she saved their lives way back. They don't like doing the things that they do, but they do them anyway because their lives are in danger when it comes to the Triad. When Moira hires them to assassinate Malcolm, they find out the reason behind the bold move, the Undertaking, and come to tell the vigilantes in order to try and stop it.