The Storm (The storm)

Humbled soldiers of the hive.

Image not owned by me.

Describe a predator in your setting with an unusual killing method
Sometimes, in a Corner, something will fall in and die, like any other does. But the thing is, sometimes the Corner will spit it out in the middle of deforming it, so then the thing will become violent and confuse everything that comes in contact with it with the Corner. That is the Storm
So it kills by inserting itself into the person it’s intended to kill. And then it eats itself as the person; it’ll come out after the person is dead, but will take the victim’s body and live their life as that person. Though after they’ve become bored, the parasite will go back to the Corner to make their body appear as a Storm again.
The public is aware of this creature, and have made efforts for the federation to notice this issue, but legal actions are not taken yet.

Inspired by Spiritfarer.

So basically, they kill by finding a person, 
Mind control them, 
 And then eats the victim while inhabiting their body. 
Most times, the Storm won’t eat the victim fully, and will continue to inhabit their body. It will live the victim’s life normally, but will be violent towards others. In very few cases, the creature will not be violent towards outsiders, and life a long peaceful life as the victim.

The Storm looks like a usually small cloud of mist or fog. Around half the size of an average person. It floats around the base of islands and searches for victims.

The Storm is fairly common around the northern part of the known area of Reverie. Corners are pretty rare around the northern districts, but they are destructive in nature, so more Storms are from the north. 
Storms can be created from a collection of random things, anything can become one if given the conditions:
First, to be trapped in a Corner.
Second, to be slowly recycled by it after death or decay.
Third, to be malformed by the disorder of excess stuff or an error happens during the exiting out of a Corner.

There is a group of dedicated activists working towards Storm regulation, they are located in the mainland, and in areas outside of the Federation. These individuals are well-known in Reverie, more and more people are joining their efforts lately given the popularization of Storm awareness media.