Hell and Hellion — Olivia Waite

This book is a sequel to Damned If You Do, but can be read as a standalone.

Last year Virginia Greening made a perilous journey into Hell to rescue the man she hoped to marry. Instead he wed someone else -- and Virginia's only reward is an uncomfortable ability to see the demons who haunt the upper ranks of society. How do you make polite conversation when something green and evil is leering at you over another person's shoulder?

Incubus James Grieve is intrigued to realize one evening that a brown-haired mortal woman is staring right at him. Her unique ability to see him is soon eclipsed by the power of their mutual attraction. James has no soul to save, and Virginia's soul is off-limits by infernal decree, so it isn't long before they're indulging in any number of passionate sins and pleasurable vices.

Until, that is, James acquires a soul of his own.