The is Christine Feehan's Dark series from her website
1. Dark Prince 2. Dark Desire 3. Dark Gold 4. Dark Magic 5. Dark Challenge 6. Dark Fire 7. Dark Dream 8. Dark Legend 9. Dark Guardian 10. Dark Symphony 11. Dark Descent 12. Dark Melody 13. Dark Destiny 14. Dark Hunger 15. Dark Secret 16. Dark Demon 17. Dark Celebration 18. Dark Possession
1. Dark Prince
2. Dark Desire
3. Dark Gold
4. Dark Magic
5. Dark Challenge
6. Dark Fire
7. Dark Dream
8. Dark Legend
9. Dark Guardian
10. Dark Symphony
11. Dark Descent
12. Dark Melody
13. Dark Destiny
14. Dark Hunger
15. Dark Secret
16. Dark Demon
17. Dark Celebration
18. Dark Possession