The Universe Reaper is a fusion of River Person and Gaster that puts a swift end to suffering and dying AUs, practically mercykilling them. Originally, they also destroyed AUs and timelines that were naturally in a state of suffering, such as Underworld and genocide timelines, not caring about the author's wishes. However, a lomg conversation with Ink!Sans after he confronted them about it made them change their mind. Now, they only end AUs that are damaged beyond repair by Out!Codes or other out-of-universe reasons.
They originated from an AU where the River Person was a closer follower of Gaster, and ended up shattered across time and space together. Eventually, some of these pieces found each other, creating this fusion.
The Universe Reaper consists of a black hooded cloak that floats without a body, with the cracked smile of the doctor appearing in the shadows under the hood. 2 floating hands accompany it, one holding a scythe.
They keep most of River Person's enigmatic mannerisms, but are more serious and somber.
They can end the flow of time in an AU, allowing them to destroy it without anyone from the inside noticing before it is too late. They wield a magic scythe and can use bones to attack