The Medium's Possession - The Cloaked Series, #2

One year after the death of her boyfriend, Cecily is ready to re-launch her life, starting with moving her over-worked sister, Zander, back to Seattle. The trouble is Scott-the sexy, tattoo artist brother of Zander's boyfriend-who is making the move, too. Crushing on Scott while her ex literally haunts her is awkward... and apparently unavoidable. Ah, life as a medium. Scott fell for Cecily the first time he heard her voice.
There's only one problem: she's Zander's little sister, and crossing that line risks the newfound balance he's fought for-and a secret he's been keeping for too long. When Zander's behavior becomes erratic, they blame the pressure of the move-until she spirals in ways more supernatural than stressed. Cecily and Scott band together, navigating their attraction while helping to save Zander from the hidden darkness consuming her.
But to banish the evil, they need a witch-and she might not make it in time.