Third in the Xenogenesis series (Adulthood Rites, 1988), exploring the impact of the kindly but implacable alien Onkali upon an Earth devastated by nuclear war. Most of Earth's surviving humans are unable to reproduce without Oankali aid; the aliens, you see, collect and engineer genetic material and will eventually develop a new race, a fusion of human and Oankali. However, from compassion the Oankali have given the humans who reject Oankali aid the planet Mars to colonize and develop as they will. Jodahs, then, is not only a "construct" (mingled human and Oankali) but the first construct ooloi--or third (neuter) sex that mediates reproduction. Jodahs is also well into its final metamorphosis (per the title), when it will grow sensory arms, develop powerful abilities to heal, and feel an overwhelming urge to seek mates. Unfortunately, the Oankali mistrust Jodahs' ability to control its talents. Banished, therefore, from human-Oankali colonies, Jodahs comes across a rare, isolated colony of wild, fertile humans; thus it is able to select mates--siblings Jesusa and Joao--and cure them of inbred genetic defects. But Jodahs' ooloi sibling, Aaor, is less stable and accomplished than Jodahs, and might well die unless mates can be found for it. Another well thought-out, often absorbing exploration of human-alien sexuality. What's lacking here is narrative tension--a sense that any of this really makes a difference to the larger designs that Butler has previously sketched in.