When does Fledgling return?

Fledgling is a science fiction vampire novel by American writer Octavia E. Butler. It was the author's final book published before her death in 2006. The novel tells the story of Shori, a 53-year-old member of the Ina species. The Ina are nocturnal, long-lived, and derive sustenance by drinking human blood. Their relationships are symbiotic, with Ina's venom providing significant boost to their humans' immune systems.