Isaac Asimov was one of the Founding Fathers of modern Science Fiction, and one may think that his writings were concerned only with highly scientifically ponderous topics, like Psychohistory and the Laws of Robotics, with little concern for more mundane topics. And yet love and sexuality did interest the Good Doctor, and often strange sexuality at that.

See, for example, the story "Satisfaction Guaranteed," when a woman falls desperately in love with his humanoid service robot; or the strange relationship between the Detective Eljiah Baley and the again humanoid Robot Daneel Olivaw. The affection between the two is so strong as to be called "Love" by Elijah. In a weird and funny story called "Playboy and the Slimy God" two asexually reproducing aliens are at odds in understanding the meaning of human sex.

But the very masterpiece of Isaac Asimov in that aspect is The Gods Themselves. In the central section of the novel we see the intimate sex lives of strange energy beings living in a parallel universe that are trisexual: one sex is called Rational, his scientifically and philosophically minded, it carries the semen, the second is the Emotional, as the name says, is rather prone to sentiments and passions, and it transmits the semen of the Rational to the Parental, the third sex, that´s especially adept to care for the young and hosts them before birth. To procreate, the three must co-penetrate in the ecstasy of love, losing consciousness for increasing periods of time, until another trio has been brought to life.