… alright, fair enough, i guess it’s about time i introduce him TvT since you were so sweet and asked- and thank you, by the way, sweet anon! you’re too kind ;///;
this is Grim Sans… aka Grim, heh.
he’s permanently trapped between the void and reality.
in his efforts to regain Gaster after his ‘erasure’, someone sabotaged his machine - resulting in it backfiring as he was partway in. everything in his world was effective erased - and all the monsters were sent to the Void, their magic and the brief rebound effect of the barrier the only thing that kept them in the Void rather than just… gone.
as it turned out, the Void is essentially a reality-adjacent dimension, and effectively overlays any and all realities. in the end, the monsters of his world - now reunited with Gaster - settled in the Void over a peaceful timeline where monsters have been since freed.
Grim, however, is unable to join his family and friends. because he’s split between realities, if he spends longer than an hour in the Void he begins to melt and lose his mind, and would eventually be completely lost and unable to be saved.
as such, he now effectively ‘haunts’ the surface. he cannot interact with living things that have not touched/seen the void, and his magic is similarly tied to the void and cannot interfere with the real world unless it’s been transferred into/through the Void.
one thing about the Void, though - it is the place souls travel through in death. so there are people in reality who can see him - but only when they are on the cusp of death and their souls are close to shattering. at that point they can see him, talk to him - or perhaps more crucially, he can talk to them. he’s been stuck like this for a long time, and while he is able to check in on his friends and family on occasion, and eventually he was able to get a phone modified by Gaster and Alphys to be able to send and receive messages via interdimensional box (as the tech is Void-based), he’s lonely. once he realized those souls close to death could see him, he started talking to them, or if possible, trying to help-
… and that’s when he got the nickname Grim. turns out even in a reality where monsters were freed, humans suddenly seeing a skeleton in black when they’re dying is a little too on the nose.
so now Grim wanders about, researching ways to bring more tech and connections back to the monsters in their new settlement - where they’re learning how to work their magic in the Void, how to run wireless tech again (wifi isn’t Void-friendly, not yet), and catching them up on human history - he sends what he can via interdimensional box. he also has a penchant for dark humor (of course), retro and pixel-type videogames (shhh), and may or may not really like maple syrup.
… help me i think way too much about him and the things he gets into and gah guys he tries so hard