@kara_dreamer Y'know, that's a good question, and I think it speaks to kind of... the storybook nature of Undertale as a work. A royal guard exists, despite there being nothing in the universe for it to guard against, right?
I think I like the thought of "amorphous blob shadows that periodically show up" more than anything. Other monsters? Infighting? Then suddenly you've introduced Game of Thrones politics, and that feels... more than just wrong to me. Like violating something sacred.
Course, that's just my take.