A symbiotic lifeform permanently bonds with its host and radically transforms the host organism.


Imagine a symbiotic life form like the [Klyntar](http://marvel .wikia.com/wiki/Klyntar_(Race)) species from Marvel: a creature made up of an amorphous mass of cells and are, as a whole, sentient.

The species would have the following additional characteristics:

  • they could only form one permanent bond with a host
  • they could evolve the host in any fashion or change its form at will
  • it would merge with the host at a molecular/genetic level and preserve its consciousness via adding its cognition center to the host body permanently along with decentralizing the host nervous system to speed up cognition via entangling the neurons together so the host will not die if shot where previous brain was
  • the host would receive enhanced healing, strength, speed, intelligence, and depending on the environment that the host lives in the symbiote will adapt the host beyond current capability's.
  • the symbiote could communicate with the host, allow them to support one another emotionally and physically during their nearly infinite lifespan.
  • In such a life-span that while technically immortal the host and symbiote would not survive forever due to war, violence, etc
  • symbiotes would make people invulnerable to disease, poison, radioactivity, and cancer (note that anything else that could detrimentally harm the host body would also be mitigated through the enhanced abilities)
  • the symbiote could only override the will of the host if either knocked unconscious (accident or combat) to save the host from harm or with the hosts explicit permission
  • the bonding would only be consensual or through birth (i.e. hosts and symbiote would mate)(the infants would grow up at a decelerated rate i.e. 1 standard year of growth would be doubled for the infant (36-40 years to adult-hood)) -they would be two separate entities with distinct personalities but they would each give the other suggestions as to what or what not to do
    • the bonding to a degree would not be personal choice but rather a gut feeling and the use of what would be best for both rather than one (i.e. telepathic subconscious decision)
  • the host would gain the innate abilities of the symbiote (i.e. telepathy, a morph-able body and any other abilities that were only innate to that specific symbiote)

  • the bonding process could last a while (i.e. 1-2 days all the way up to a year or two in rare cases ) so the bodies have time to merge and develop


Most sci-fi focuses on the physical side of such a bond (e.x. Venom, Carnage) or parasitism involving possession or overpowering of the will in such a theme as this it is stated to be an extreme case of parasitism. Not much is is written about the other route and what will happen with extreme symbiosis between two organisms and the psychological effects such a bond would have on the host and symbiotic organism in such a bond.


Given stated examples what long term psychological effects could happen to a given host after a log period of time?

  • $\begingroup$ Could you break this up a bit? Pretty much your entire question is an enormous six-line sentence and it's very hard to read. Or maybe I'm just tired, idk. $\endgroup$
    – F1Krazy
    Jan 11, 2019 at 23:01
  • $\begingroup$ 1. F1Krazy is right. Use punctuation. It's free and it makes your writing easier to read. It will improve your grades, if you ever get graded on what you write, 2. Check out the tour. Open ended discussion of upsides and downsides is not a question according to the site rules. How about reformat this into a specific question about some aspect of your symbiote. You can post a number of related questions all about the same symbiote. $\endgroup$
    – Willk
    Jan 11, 2019 at 23:40
  • $\begingroup$ You also make some assumptions here that are not stated explicitly. Why does a symbiotic relationship give the two distinctive creatures "infinite" lifespans? You keep using the word "evolve", and that's certainly not accurate. $\endgroup$
    – jdunlop
    Jan 12, 2019 at 0:24
  • $\begingroup$ can you remove the hold on my question please I have specified the question and have added some of my own research into this topic. @jdunlop please do not criticize this question I am working on a concept that I find interesting and I just want some input to this question $\endgroup$ Jan 15, 2019 at 20:12
  • $\begingroup$ There is one small problem that can be easily fixed. The question in the title is different from the question in the body of the text. Physiological downside (title) versus long term psychological effects (text). Please choose which question you want answered. WB prefers a single question format. You can ask the other question separately. $\endgroup$
    – a4android
    Jan 20, 2019 at 3:39

2 Answers 2


The biggest downsides I can see are evolutionary in nature.

  1. What happens with reproduction?

Consider the case where this happens on a world without space flight. If reproduction happens in the host species as it did before the symbiotic union, and the symbiont also reproduces, whether it happens with the host species or separately, then eventually you end up with more immortal being than can comfortably live on the planet. And, depending on how long a generation is, we're talking centuries at most, not millennia.

If the host stops reproducing after symbiosis, but the symbiont does not, then what happens when there are free symbionts around without beings to go into symbiosis with?

If the symbionts don't reproduce (a possibility if they are an artificial construct), then you end up with immortal "gods" and mortal beings side by side, and there will never be more of them.

Subquestions include:

  • If overpopulation occurs, do we end up with some sort of "survival of the fittest" competition for resources? Or do groups start researching methods to kill off the excess immortals?

  • If infants are born immortal, do they grow up? If so, where / when does aging stop? Or do you end up with decrepit immortals and infant immortals, never changing?

  • What sort of societal stresses do you get when there are a group of immortals that eventually (simply through the passing of time and absolute boredom) own everything, control everything, and run everything?

  • How immortal are the beings? Can they survive plunging into the sun, or free-falling from the edge of space? Or do they simply not die of aging and disease, but violence and accidents can kill them?

    • This modifies some of the basic questions. In the case of overpopulation, the most violent and those that resist damage and death best survive. Eventually, you end up with a small population of Doomsday (the thing that killed Superman) class beings with intelligence.
    • In the case of a limited number of symbionts, then the world devolves into a struggle to obtain one of the symbionts (which won't happen, because they bond with only one person). Multiple possibilities here, including that society bans adults from moving, so it will eventually become obvious who is immortal. Or, the symbiont pairs develop chameleon-like abilities to change their apparent (or their physical) age - reverting to an infant is probably better than being killed. Or that people realize what is actually happening, then rounds up all symbiont pairs and isolates them somewhere, allowing society to continue as normal. Or...

Really, there are all sorts of possible downsides. It depends on what the specific parameters that you offer are.


This is a question I've been thinking about Myself, and a thing I've hit upon the more I've looked into it is that maybe the best place to start is to confirm the answers to a few MORE questions, and use what you decide for the answers to inform your research about things like the Psychological Impact this might have on both the Host and the Symbiote (which seems to me like it might be one of the bigger determining factors on how the two will affect each other- the science of the biology involved might be a bit more fungible depending on the setting, but how these bodymates deal with any physical aspects of their symbiosis will probably be influenced by how they react psychologically to their situation):

-Was the process that resulted in this "bonding" Consensual on the part of the Host?

-Do your two organisms experience their shared existence as being Two Separate Entities sharing a body, or One Entity that combines traits of Both?

-Does the Host retain their Free Will? Or are they overridden to some degree?

-How much control do the two share over the host's body? Is only one doing most of the "Driving"? Do they take turns?

-If they are Two Separate Beings, how do they balance their individual desires, personalities, and motivations?

-Do they share Memories? Or do they each have their own?

-What was the host like before they became a Host? Did the Symbiote have a personality or self-awareness beforehand? How are the two different?

Your question is a good one, but unfortunately the answer seems to be "ask and answer more questions, and go from there"... I'm sorry if this isn't terribly helpful, but this is the advice another friend gave me, and answering these has really helped flesh out my own species of host-symbiote composite beings, so hopefully it will at least help you narrow down the direction you want to go with this a little more? I hope you find what you're looking for! :D

  • 1
    $\begingroup$ Well done. You have considered the issues raised by this question. Parasitology was part of my scientific education. Symbiosis or parasitism are never consensual. However, this concerns an intelligent symbiote, so may be it might be a different situation. Keep up the good work. I hope to see more posts by you here on WB SE. $\endgroup$
    – a4android
    Jan 20, 2019 at 3:56

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