Book Two of the Cluster Series, “Chaining the Lady” came out in 1978.
If there is a funnier or more thought-provoking Science Fiction novel I haven’t read it.
The story revolves round the concept of Kirlian aura. Space travel is too expensive and takes too long, transporting physical matter huge distances. Instead beings transmit their “aura” into a host, and space travel is accomplished through a form of spiritual possession.
The Andromedan galaxy has exhausted their energy and seeks to invade the Milky Way galaxy to steal ours. By accident a young human officer discovers that a high ranking alien has been made an involuntary host. Just in time the Milky Way is alerted to the existence of invading high Kirlian auras from Andromeda – but they don’t know who they are.
Melody of Mintaka from the music sphere, the highest aura available to the Milky Way is conscripted and projected into the body of her voluntary host, Yael of Dragon, a gorgeous young woman, quite street savvy but not very bright. Melody is extremely intelligent but she is not an organic form – her body’s natural form resembles a percussion band. Not only is she elderly, a reclusive Tarot philosopher, but she is something unusual even in Mintakans. The Mintakans change gender when they mate. Due to a mis-mating at her first attempt, Melody is rendered neuter.
Piers Anthony with his customary sexual humour creates a great burlesque out of the personality combination of a voluptuous healthy young human and the elderly Mintakan neuter. The internal character play and the tactics the joined personality elect to use is milked for maximum humour. This alone makes the book worth reading. I challenge anyone to finish it without aching sides.
But the core idea, of the military application of a fifth column by mind possession is truly unsettling.