It's very interesting to hear you don't seem to be interested in the Deltarune Gaster Theorizing side of things, considering how much your AU incorporated Gaster into things. I'd figured you'd of been a bit more interested in it. Is there any particular reason it doesn't fetch your interest?
It's hard to say sometimes why something does or doesn't catch me really. I'm not super interested in larger Deltarune theories or predictions in general at this point since in every new chaper I'm completely blindsided by everything so I'm just along for the ride. But I think fundamentally UT Gaster (as fanon knows him) and DR Gaster (as fanon knows him) are completely different.
First, this all relies on the assumption that the mystery man in UT is Gaster, and the other being or force or voice or whatever in DR is Gaster, and both of those things are not confirmed. I think people just take it for granted now because the fanon around them both has gotten so strong, but we have no confirmation for either of those things. Shout-out to the weird drippy thing that DOES speak in Wingdings in that beta room
Anyway, working off that assumption, UT Gaster is an incredibly secret character. In the first releases of Undertale even, the values in the .ini file were broken so you couldn't even run into him naturally. You'd have to go in manually to edit the values, and to do that you'd have to learn from someone else that he even exists in the first place. Even now you can play Undertale like a hundred times and never see him or even know he exists, and he has no impact on the plot or anything. He's a big easter egg. he's in hiding
DR Gaster, as fandom tends to treat him right now, is some kind of massive game-defining unknowable force, puppeting around characters and moving them around on some inscrutable chessboard for his own mysterious ends. He's everywhere and can see everything, he's behind everything that happens, every mysterious or strange thing that happens is Gaster's fault. He's so powerful he can define the game's logic, he can break the fourth wall, he can post on Twitter, he can do everything and everyone's just pawns in his master plan. He's right in your face right from the beginning making you make vessels and such or whatever, he talks to you directly repeatedly about "his" Deltarune.
Like... these two versions are about as diametrically opposed as you can get. And the thing is, with the godmoding and fourth wall breaking attributed to DR Gaster a lot of the time, there's no potential for him to be any kind of character. UT Gaster could be something, anything, because we knew so little about him and he was barely even there. He could just be A Guy. DR Gaster feels more like a big deus ex machina. DR Gaster doesn't have any room for a personality or a character arc or growth or development, he's just off on the sidelines being cryptically smug about his secret plans. It's just less interesting to me. But that's just me.
