Asimov, Isaac The Gods Themselves. 1972, That's my favorite Sci-fi novel of all times; the aliens come in triads; one is the rational, the other the emotional

Asimov, Isaac The Gods Themselves. 1972, That's my favorite Sci-fi novel of all times; the aliens come in triads; one is the rational, the other the emotional the third one is the parent/Mother. They have sex by melting into each other, when they become one - because the weak nuclear force is so weak in this universe; Pure Genius.