You Lucky Witch by Marie Mason
Roark knew his brother was unhappy in the pit of hell but he never expected him to try and escape. Now it was his job to bring him home. Kayley was a witch whose DNA made it difficult for her to cast spells. Well, spells that worked. When she inadvertently helps Roarkās brother escape, he refuses to let her go in case she causes more trouble. Who was she to argue with a demon? Especially one as fine as Roark.