Fun Fact to think about:
W.D. Gaster.
Now, I know this sounds weird to anyone who's never heard of him. Basically, he's this melted-ish blob which looks like a Skeleton injected with DETERMINATION(Undyne in Geno). The fandom represents him as a scientist with a black/dark gray turtle neck and a lab coat.
Since there's not much info on him, I've gone from post to post, trying to fit a bunch of theories together. Here's what I believed happened:
Gaster fell into his creation, as stated. We generally assume his creation to be the CORE(I think it was stated somewhere else that his creation actually WAS the CORE, but I dunno.) When he fell in, the power kinda imploded and he absorbed it. Since his magic body couldn't hold it all, he kinda melted like he was injected with DETERMINATION. He was scattered through countless dimensions, SAVES and RELOADS. In the end, I believe he was wiped from everyone's mind. He can only come back when you mess with the files(setting your Fun level to 66 in Waterfall, I believe, will open a gray door). Since he was scattered, I think that, like Chara at the end of a Geno run, he can attack the files. Instead of attacking them, he just kinda makes his presence known to the player, whether through the gray NPCs or the actual door leading to him. Since he can't completely see what he's doing to the files, he's just messing with them and hoping someone will find him(or something).
Also, if W.D Gaster stands for Wing Din Gaster, he could have something to do with the Dreemurr bloodline.
Wing Din Gaster
Wing Ding Aster
Aster is a type of flower and Wing Ding is a type of microsoft font, not unlike Sans and Papyrus. He could possibly have something to do with both bloodlines.