Reaper's Rite Series by Dorothy Dreyer

Sixteen-year-old Zadie’s first mistake was telling the boy she liked she could bring her dead sister back to life. Her second mistake was actually doing it.When Zadie accidentally messes with the Reaper’s Rite that should have claimed her sister Mara, things go horribly wrong. Mara isn’t the same anymore—Zadie isn’t even sure she’s completely human, and to top it off, a Reaper is determined to collect Mara’s soul no matter what... moreSixteen-year-old Zadie’s first mistake was telling the boy she liked she could bring her dead sister back to life. Her second mistake was actually doing it.When Zadie accidentally messes with the Reaper’s Rite that should have claimed her sister Mara, things go horribly wrong. Mara isn’t the same anymore—Zadie isn’t even sure she’s completely human, and to top it off, a Reaper is determined to collect Mara’s soul no matter what. Now Zadie must figure out how to defeat her sister’s Reaper, or let Mara die … this time for good. less

Months have passed since Zadie faced her sister’s Reaper, during which time she's been under her mentor's magical protection. But now that she's turning 17, that protection is about to run out. When dark forces lure Zadie to wander at night, she's manipulated into committing unspeakable acts. With her friends and family at risk, Zadie must try to use her powers to break free from the Reaper's grasp, or surrender to the Reaper's Rite, which can only lead to death.