Meanwhile the surviving humans have been brought aboard the Oankali starships. Over a period of centuries the Oankali attempt to learn how to communicate with the humans and to prevent them from killing themselves when they realize that they are now essentially the slaves and study subjects of an alien race. Eventually we are introduced to a woman whose name is very eventually given as Lilith with whom an Oankali of the ooloi gender (the Oankali have three genders: male, female, and ooloi) finally establishes a relationship. The ooloi begins to teach her (and us) about the Oankali and the plans they have for humanity. What they want from Lilith is somebody to help wake up more humans and acclimatize them to their situation.
What we learn about the Oankali is that they consider themselves genetic traders. They travel the stars looking for interesting genesets that they can appropriate to mix with their own ever-changing geneset, although they do have one starship dedicated to Oankali of the geneset they had on their home planet. The ooloi gender is a kind of genetic engineer. They can store genetic information in memory and in an organ that they use for collecting cells from organisms they encounter. When they mate with males and females, they take genes from all three mates (or more, if there are more) and mix them into a new pattern with an optimum outcome in mind. That's what their gender does. They are also capable of fixing genetic problems that lead to disease, but when they discover cancer in humans they consider it not just a problem but, once properly understood, the key to beneficial side-effects such as being able regenerate lost limbs and organs. The Oankali are very excited about the possibilities inherent in cancer.
The ooloi, and I guess the Oankali in general, can also physically merge with other living organisms and can directly stimulate a nervous system, if there is one. One of the things the book explores is the idea of consent, and what it means when a) the being you are consenting to can correct your genetic flaws and make you stronger and healthier, and b) the being you are consenting to can make you feel pleasure greater than any you've experienced in any other way through direct stimulation of your nervous system. The ooloi are capable of understanding your desires on a direct biochemical/neurological level, and within the context of the novel they often understand what an individual human wants better than the individual understands themselves. So is it rape if the ooloi perceives that the human really does crave the level of pleasure the ooloi can provide, even if the desire causes conflict on the conscious level with the desire to be autonomous?
Butler maintains an uncomfortable ambiguity on the question as she slowly explores Oankali culture and humanity's various reactions to it. There's never any doubt that humanity's choices are limited by the Oankali, but as the Oankali merge the genesets of the two species, the resulting new species is more sympathetic to humanity's stubborn resistance to total co-optation. It's also more adept at overcoming that resistance by offering humans the things they truly desire. Are they in fact better at enslaving humans? It remains an open question.
There's a lot going on in this book. It's a novel of ideas that explores gender, sexuality, reproduction, genetic engineering, free will, consensuality, appropriation. Butler is not a literary writer, and her prose is very plain and direct. What she does, however, is follow her premises deep into their own internal logic, which gives them the dreamlike feel of being truly lived in, truly living. The Oankali world seems to unfurl according to its own reality. We start to feel what an ooloi wants, what it craves, and that begins to shift our ideas about what male and female mean. In a way, the focus of the novel is what it would mean for humanity to have an ooloi gender as part of its reproductive process.
But it's a lot more than that. I started off feeling that I'd never read anything like it, and it's true that Butler has achieved something unique here. She has carved out a niche that will no doubt keep her name alive in the field for a very long time. However, early on the Oankali preference for symbiotic organic technology (e.g. living space ships and suspended animation modules) reminded me of Varley's Nine Worlds and Gaia stories. The way that humans are transformed into something deeply, weirdly alien by their encounter with the Oankali reminded me of Cherryh's 40,000 in Gehenna.
Also similar to Cherryh is the way that sex and rape are uncomfortably intertwined. It's impossible to say that the Oankali aren't raping humanity, but it's equally impossible to say that they aren't learning through the process how to give humanity what they really want, which is the freedom to choose their own path, even if it only leads back to self-destruction. There's no simple morality to be derived from the story, as far as I can tell. There's a sense that rape and perhaps enslavement are inevitable and that all you can do is deal with the consequences the best you can.