Imago is the concluding volume in Octavia Butler's Xenogenesis trilogy and one thing that should be apparent by the time the readers gets more than a handful of pages into Imago is that Octavia Butler has written a trilogy in the more classic sense of the term. Butler's trilogy is a collection of three novels which tell otherwise complete stories that while they expand on the previous novel, each novel does not depend on the other to stand. Octavia Butler's trilogy is three stand alone novels telling three stories related in theme and setting and that builds an overall story arc as well as three smaller story arcs.
Imago is the story of Jodahs, the latest Oankali / human hybrid child of Lilith Iyapo. An interesting thing about the Oankali child is that as a child their gender is not set, so depending on the stimulation and experiences given to the child, the child may develop into a male, female, or ooloi (a third gender). Up until this point no construct (hybrid) children have been permitted to develop into ooloi because the Oankali have had concerns about how they would develop and it was only recently that male hybrids were permitted to develop. Jodahs, of course, develops into an ooloi hybrid rather than the male he, or it, was intended to be.
The story of Jodahs is one of isolation and dependence and the reader gets to experience the anxiety Jodahs feels and experiences from his community (an ooloi always needs to find a new home because of sensory differences with those in the home it was raised in).
We are now at least several decades, perhaps longer, from the events of Dawn and Adulthood Rites so Butler reveals some of how the Earth has developed and how the Oankali / human project has progressed. We learn that the Mars colony that was proposed in Adulthood Rites is a success and giving humanity the only chance to survive unchanged.
Imago is written with a strong sense of character and Butler describes the alien culture in such a way that it feels authentic and the hybrids in a way that we can see why some humans would never accept them, but also why others have accepted the Oankali.
As always, Imago and the Xenogenesis trilogy is an examination about race, differences, fear, prejudice, the future, and identity. As always, Octavia Butler does an excellent job with her storytelling. And, as is the case with the two previous Xenogenesis novels, Imago is a very strong work of fiction but somehow less outstanding than some of her other work.