In a SciFi world I'm building with other people, we'd like to create a planet with an infection outbreak going on. There are wildlings. They are pretty primitive, have stone tools and wood houses. They are human-like. The wildlings are getting infected and when it happens, they become highly aggressive, their appearance changes and they have a hive-mind (meaning they are all connected to each other, know what each other thinks and are controlled by a queen).

The infection comes from a gigantic underground beast. This beast grows trees that are spreading the outbreak, meaning the infection of wildlings comes from those trees. It is the beast that is controlling the wildlings. So if the beast is killed, the infected stop, the trees die and the infection stops.

What could be a scientific reason for this infection? What does my beast need to provoke such changes to wildlings?

Important aspects of the infection

  • Infected are highly aggressive
  • Infection comes from the trees growing out of the beast

Changes caused by infection: (please try to keep as much as possible)

  • Hive-mind
  • Changing in aspect
    • Black skin
    • Claws / fangs / other means of attack

Please note:

Time can be a factor to explain any of those aspects.

  • $\begingroup$ What's wrong with rabies as a model for an infectious disease which increase aggressivity? I can't help with the trees part -- maybe the beast somehow infects the trees with a fungus? $\endgroup$
    – AlexP
    Aug 25, 2017 at 12:12
  • $\begingroup$ @AlexP Well, it's just that we want the beast to be hidden for some time and the infection appears to be some kind of magic at first. Rabies would be something too "common". But the fungus part can be viable, yes :) $\endgroup$
    – Keker
    Aug 25, 2017 at 12:16
  • 1
    $\begingroup$ Rabid hibernated animals... with spring they wake up and merrily start biting around... $\endgroup$
    – L.Dutch
    Aug 25, 2017 at 12:20
  • $\begingroup$ I think this very much depends on what these 'trees' really are, in order to be consistent with known biology. If they are indeed actual plants grown specifically by this beast, I'd consider making seedlings or pollen your vector; if the trees are actually great fungal growths, spores; if a literal extension of the beast itself, some sort of hormone or similar secretion. $\endgroup$
    – MSet
    Aug 25, 2017 at 12:36
  • $\begingroup$ @MSet Well, I wasn't too specific on that. Honestly, I'm interesting in what you guys can come up with. I'd say that it has to look like a tree, but can be anything you said. I don't know if it helps you or not, but I don't want to give too much constraints. $\endgroup$
    – Keker
    Aug 25, 2017 at 12:39

4 Answers 4


One potential method: the lifecycle of the host organism is complex and evolved to include four different organisms. A fungus, the subterranean beast, the wildlings, and a worm.

The fungus infects the worm, which then is either eaten by the beast or the worm itself is also a parasitic organism that infects the beast. The beast spreads out long appendages that resemble trees that it uses to collect nutrients, water, and oxygen from the surface. This is something that the beast just does, whether it is infected or not, but the fungus has hijacked this process to spread its spores throughout this network.

Once spread to the 'trees', the spores infect the wildlings. Like Cordyceps, it causes a change in behavior in certain organisms that it infects. In this case, it makes them aggressive and causes growths of black 'skin' and 'claws'. The skin is actually a covering of the fungal spores - the same spores present in the 'trees', so the aggressive behavior helps to spread it further. The 'claws' are a by-product of a change in the production of keratin.

The hive mind is accomplished through pheromone communication. We know that plants actually have rudimentary forms of communication - it doesn't sound like too much of a stretch that a fungus could.

The "queen" is really the colony of matured spores living in the subterranean beast. The juvenile spores also communicate with one another. Granted this can't go long distances, but 'messages' can get passed along a chain.

The ultimate goal is for the infected wildlings to die, whereupon they become food for the larval form of the worm that then infects the beast.

  • $\begingroup$ This is a really great answer. I love the fact that the black skin is actually fungus. The change in keratin would take time, though, which could be an indicator between recent and old infected. I'll have a hard-time choosing the right answer! $\endgroup$
    – Keker
    Aug 26, 2017 at 10:47

An enhanced version of Ophiocordyceps.


The monster is a fully mature adult. It is a massive conglomeration of the many of the creatures it has infected. At this stage it can produce egg stage of its life cycle. (Tree like fungi)

It uses its controlled servants to plant and tend these 'Eggs'. These eggs are simply a specialized organ of the fungi. The adult monster needs a minimum mass to grow these successfully. They can be detached, but require constant tending. (Food)

The eggs then release spores of some sort (from traditional earth fungi spores to Aliens face huggers. They infect a new host and slowly grow and develop. Once they reach maturity they can control the host and respond to the synaptic impulses of monster (if within range). This is the larval stage of their life cycle.

The larva can infect others directly. Simple close proximity over a long enough time might suffice. But bodily fluid contact greatly increases the infection rate.

Once the larva density if high enough at a great enough distance they can form into a new monster hive/conglomerate. This is when they reach the adult stage of their life cycle.

  • $\begingroup$ This is a really nice answer! I love the fact that there are eggs that allows it to spread not only from individuals, but to other places on the planet too while keeping the hivemind. $\endgroup$
    – Keker
    Aug 26, 2017 at 10:39

The Thorian

If you played Mass effect at some point you found an ancient creature that produced spores all over the planet, staying in constant contact would produce a telepathic connection with this entity, transforming all the colony into loyal servants where every thougth was audited.

This entity could create thralls from "blueprints" (aliens keep in stasis) to protect his body. This thralls would produce poison and have claws to attack any intruder.

The captured colony would fight as an unified team under direct command of the entity to protect it.


The parasite could mess with the host neurotransmitters, essentially inducing pretty much any mental illness. Evolution-wise, to make the infected hosts highly aggressive is much more effective for the beast's purposes than, let's say, generalized anxiety disorder or major depressive disorder.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .