The Dark Cycle Series by Rachel A. Marks

Aidan O’Linn’s childhood ended the night he saw a demon kill his mother and mark his sister, Ava, with Darkness. Since then, every three years the demons have returned to try to claim her. Living in the gritty, forgotten corners of Los Angeles, Aidan has managed to protect his sister, but he knows that even his powers to fight demons and speak dead languages won’t keep her safe for much longer... moreAidan O’Linn’s childhood ended the night he saw a demon kill his mother and mark his sister, Ava, with Darkness. Since then, every three years the demons have returned to try to claim her. Living in the gritty, forgotten corners of Los Angeles, Aidan has managed to protect his sister, but he knows that even his powers to fight demons and speak dead languages won’t keep her safe for much longer.In desperation, Aidan seeks out the help of Sid, the enigmatic leader of a group of teens who run LA Paranormal, an Internet reality show that fights demons and ghosts. In their company, Aidan believes he’s finally found a haven for Ava. But when he meets Kara, a broken girl who can spin a hypnotic web of passionate energy, he awakens powers he didn’t know he had―and unleashes a new era of war between the forces of Light and the forces of Darkness.With the fate of humanity in his hands, can Aidan keep the Darkness at bay and accept his brilliant, terrifying destiny? less

Against the backdrop of an ancient battle between the forces of Light and the forces of Darkness, Aidan struggles to control the newly awakened powers that seem to be his only hope for rescuing Ava, his little sister, trapped somewhere beyond the Veil. As he gravitates to Kara, the dangerously unstable girl who helped him realize his abilities, a terrible mistake of fate is revealed that points him back toward Rebecca, whose role is becoming more critical to the battle... moreAgainst the backdrop of an ancient battle between the forces of Light and the forces of Darkness, Aidan struggles to control the newly awakened powers that seem to be his only hope for rescuing Ava, his little sister, trapped somewhere beyond the Veil. As he gravitates to Kara, the dangerously unstable girl who helped him realize his abilities, a terrible mistake of fate is revealed that points him back toward Rebecca, whose role is becoming more critical to the battle. And no matter what his heart wants, it might be too late to stop the pieces already in motion.Without knowing the sacrifices that will be required of them, Aidan and his motley crew of friends—each with their own role to play—must face the demon threat head-on. They’re the only ones keeping the growing army of Darkness at bay, and if they fail, the future of humanity could be lost. less

The fate of humanity hangs in the balance as Aidan faces a crushing choice: give in to the demands of the forces of Darkness in order to save his sister, Ava, or fight on the side of good and risk losing her forever. With so much at stake and so little time, Aidan embarks on a mission to finish assembling a team of “Lights,” other teens whose special abilities are linked to his own... moreThe fate of humanity hangs in the balance as Aidan faces a crushing choice: give in to the demands of the forces of Darkness in order to save his sister, Ava, or fight on the side of good and risk losing her forever. With so much at stake and so little time, Aidan embarks on a mission to finish assembling a team of “Lights,” other teens whose special abilities are linked to his own. Meanwhile, Rebecca discovers that she’s more than just a normal teen, and that the power awakening inside her may be stronger than she ever could have imagined. As the city plunges into chaos and Aidan doubts his plan of attack, Rebecca’s newfound gift may tip the balance in the wrong direction.In this thrilling final installment of The Dark Cycle trilogy, will Aidan find the help he needs to release the world from Darkness’s grip? Or will he lose everything he's been desperately trying to save, including his soul? less