Been meaning to reveal this for a while now ever since I started to care more about Wandering The Surface, and I finally had the time to show it
But to explain properly on what's going on... Papyrus is technically in the role of Undyne, or at least her position
the Waterfall equivelant is sorta like a desert, so that's why it looks the way it does here
At the start of the Ruins equivelant (which is a city full of greenery) you'd encounter both Mad Dummy and Ruins Dummy with Asgore, who have a training battle with before leaving
And up until the Waterfall equivelant you would not meet them again once
Until you get to Papyrus, in which it'd be revealed he's not actually working on his own... but has teammates!

Those two teammates are, of course...
"Devious Mews" and "Admiral Fluff".
And together... they form... "The Three Musk-Great-Eers"
And would all three of them actively try to stop you in your tracks, as a team, until you'd fight Papyrus alone (for reasons I will talk about eventually, but it DOES involve Mettaton in some form)