Books like A Gathering of Gargoyles

Aeriel's love has broken the curse on the darkangel Irrylath, making him human again and freeing him from the control of his mother, the dreaded White Witch. But the Witch is far from defeated. Her wicked plans require all seven of her vampyre sons, and she will not give one up so easily. There is but a single hope for the Witch's defeat--solving an ancient, mysterious riddle. So Aeriel sets off to solve the riddle, sailing across a sea of dust and straight into the worst of the Witch's terrors. But if Aeriel is to save Irrylath and her world, she will have to overcome his bloodthirsty darkangel brothers--and ultimately confront his terrifying mother face-to-face.