Isso pode ser Os Deuses de Isaac Asimov Eles Mesmos
De Wikipedia :
O romance venceu os prêmios Nebula e Hugo (em 1972 e 1973, respectivamente) e é amplamente considerado um dos "must reads" na ficção científica.The second part takes place in the parallel universe, whose inhabitants are divided into dominant "hard ones" and subject "soft ones", whereof the latter have three sexes with fixed roles for each sex:
Rationals (or "lefts") are the logical and scientific sex; identified with masculine pronouns and producing a form of sperm.
Emotionals (or "mids") are the intuitive sex; identified with the feminine pronouns and provide the energy needed for reproduction.
Parentals (or "rights") bear and raise the offspring, but are identified with masculine pronouns.
All three 'genders' are embedded in sexual and social norms of expected and acceptable behavior. All three live by photosynthesis; whereas sexual intercourse is accomplished by bodily collapse into a single pool (known as 'melting'). Rationals and Parentals can do this independently; but in the presence of an Emotional, the "melt" becomes total, which causes orgasm but also results in unconsciousness and memory loss. Only during such a total "melt" can the Rational "impregnate" the Parental, with the Emotional providing the energy. The hard ones regulate much of soft one society, as by allocating one of each sex to a mating group, called a "triad", and acting as mentors to the Rationals. Little is shown of "hard one" society; wherefore the Emotional Dua, the protagonist of this section of the book, suspects that the "hard ones" are a dying race, retaining the "soft ones" as a replacement for their absent children. This is dismissed by Odeen, the Rational of Dua's triad, who having the most contact with the "hard ones", has heard the "hard ones" speak of a new "hard one" called "Estwald", accounted of exceptional intelligence.