Comments

I have a few theories about that!

1: Undertale and deltarune ARE connected somehow, with Undertale being some kind of dark world (It's a theory that doesn't make sense, I know, but I like the concept :D)

2: Whatever the hell happened with Dess happened in a dark world, and Asgore was somehow the cause of the dark world and/or Dess's disappearance. And maybe like not all of the town knew about the Dark World, so like he tried to explain it and all his theories, and they were like "this crazy old guy made some kid go missing, holy shit", and that's why Tori left him. I think that Kris and Asriel were probably involved in this too, but we can't know either of their perspectives for obvious reasons

I think you forget he was the king of the underground its not like this is all foreign for him he lived in a world not too different to the dark worlds for his whole life while you bring up some good points the familiarity to the dark worlds doesn't seem too crazy