Berserker Parasite

A large white centipede-like parasite born when rain falls on a fresh battlefield with a heinous body count. Eggs are formed in the mud, which hatch after a week. Once hatched it’ll attempt to find a human or other similar host.

They must gain permission from their host in order to enter them. Usually done through trickery and temptations of power. Once permission is granted they’ll crawl onto the host’s back and dig inside their spine. The process is oddly pleasant feeling. The parasite can’t be removed once it’s invited in, completely replacing the host’s nervous system.

After a day the host gains the strength of 5 men due to the parasite reweaving their flesh and bones. Whenever adrenaline is created in the host, there’s a 1 in 6 chance the host entering a violent frenzy for 1 hour. The parasite feeds off the psychic energy generated while under the effects of adrenaline.

The parasite can speak via short range telepathy. After fusing they like to keep in touch with their host. Pretending to be their friend in order to subtly goad them into situations that would make more food for it. If the parasite is unable to eat for a week it and the host dies.

There are tales of a version of this parasite that is covered in rusty brown hair. If you accept their deal you gain the strength of 25 men but whenever adrenaline is created you always go into the frenzy.

 

Author's Note.
Another magic item I found looking through old stuff. Stretching the idea of a magic item here, but I really love the concept and the implied body horror. Might have been inspired by this one movie I don't remember the name of. Iirc there were alien parasites that ate and replaced their host's spine so they can feed off their fear?

Edit: It was also probably inspired by the Magatama from SMT Nocturne. Funny little bugs.