Lacking Natural Simplicity

From the Guardian series:

• Demon Night, by Meljean Brook; copyright 2008 by Melissa Kahn; ISBN 978-0-425-21977-5.

• Demon Forged, by Meljean Brook; copyright 2009 by Melissa Kahn; ISBN 978-0-425-23041-1.

The Guardian series consists of (at least) Demon Angel, Demon Moon, Demon Night, Demon Bound, and Demon Forged. (I haven't read Demon Bound yet.) Stories by Meljean Brook appear in (at least) the following anthologies: Hot Spell, Wild Thing, First Blood, and Must Love Hellhounds.

Hide Me Among the Graves, by Tim Powers, copyright 2012; ISBN 978-0-06-123154-4.

Excellent. A sequel of sorts to The Stress of Her Regard.

From the Hex: series:

• Demons are a Girl's Best Friend, by Linda Wisdom, copyright 2011; ISBN 978-1-4022-5439-0.

• A Demon Does it Better, by Linda Wisdom, copyright 2012; ISBN 978-1-4022-3672.

These are farther to the romance side of the “paranormal romance” genre than I generally prefer.

The earlier books in the Hex series are 50 Ways to Hex Your Lover, Hex Appeal, Wicked by Any Other Name, and Hex in High Heels.