SS
Steven G. Spruill
Steven Gregory Spruill is an author of horror, science fiction, and thriller novels, best known for his "hemophage" novels: Rulers of Darkness, Daughter of Darkness, and Lords of Light. He has also written under the names Steve Harriman and Steve Lyon.
Excerpt from Wikipedia, available under CC BY-SA 4.0.
Books

Keepers of the Gate
1978
ISBN 9780440144410