The Evilist (Twyla Twilight, genie from the green sea, Saga Book 1)

Falconwood, Colorado is a snowy, cold little town high in the Rocky Mountains northwest of Boulder. Twelve to fourteen thousand feet snowcapped peaks surround the sleepy town, but Falconwood is a place where magic happens. Teenage novelist, Wayne Mallitz, discovers a bottle and the beautiful genie that comes out of it, Twyla Twilight. She gives Wayne ten wishes to make, with the stipulation that his very first wish is to love and be true to her forever and, in turn, she to him--which is an easy decision for him to make, as Twyla is deliciously gorgeous, with all the to-die-for feminine features a young man like Wayne would melt over.

Yet he quickly begins to learn some disturbing things about Twyla the longer they live together--nothing that disrupts his undying love for her, nothing could ever stop that since it was his very first wish. But Twyla's latent powers to read minds, manipulate people, and even kill by sheer will whenever she feels the need become evident to Wayne. Twyla's powers become progressively problematic and... Wayne realizes he's going to have to live with that fact forever.