[1] After the Second World War, science fiction moved towards more mutualistic relationships, as in Ted White's 1970 By Furies Possessed; Brian Stableford argues that White was consciously opposing the xenophobia of Robert Heinlein's 1951 The Puppet Masters which involved a parasitic relationship close to demonic possession, with a more positive attitude towards aliens.
[1] Stableford notes, however, that Octavia Butler's 1984 Clay's Ark and other of her works such as Fledgling,[2] and Dan Simmons's 1989 Hyperion take an ambivalent position, in which the aliens may confer powers such as Hyperion's ability to regenerate continually—but at a price, in its case an incremental loss of intelligence at each regeneration.
In the series Stargate SG-1, both the principal villains, the Goa'uld and their benevolent versions, the Tok'ra were symbionts who grafted themselves into the human nervous system.
The Force in the Star Wars universe is described by the fictional seer Obi-Wan Kenobi as "an energy field created by all living things".
[4] In the Ultraman series, the titular aliens take human bodies to rest in and hide among society, while the hosts gain inhuman levels of speed and strength.