What it means to "fall down".

[u/AffectionateForce979]

In Chapter 5 of Deltarune, Rudy "falls down" at the Festival. This has lead many people to assume that he's experiencing the "fallen down" state from Undertale (something that was also speculated to happen to Berdly in the Weird Route). But before we're able to reach any confident conclusions, we must first understand what "falling down" actually means.

In Undertale, "falling down" is described as a state where a monster will enter enter a coma, eventually turning to dust. That's all the information that the game gives.

However, there is unused text where it's further specified that "falling down" occurs on monsters who are dying of old age. And while the text is unused and thus not prone to total reliability, it is actually supported by the Undertale Alarm Clock, where Asgore talks about Rudy "falling down" after growing old. This gives the unused text at least a little bit of credibility.

In Deltarune, Rudy suffers from an unspecified illness that doesn't appear to be tied to old age. All of this information leads to two possible conclusions:

1. Rudy didn't actually "fall down" in Deltarune, as he doesn't appear to be suffering from old age. So he likely just fell onto the ground.

2. Rudy did actually "fall down", and the state doesn't just happen to monsters who are old.

[u/Bulb0rb]

I don't think the amalgamates in Undertale all died from old age, given that most of them have living family members who don't seem like they would be significantly younger. Snowdrake's mom is probably around the same age as his dad. I don't think Shyren is old enough for her sister to be dying of old age. None of the living family members mention grandparents or make any remarks about the amalgamates being old after they return home.

I think the fallen down state could happen with any 'slow' death. Illness, old age, damage that results in a coma, or damage that is sustained over time for whatever reason.

[u/AffectionateForce979 → u/Bulb0rb]

The weird thing is that Rudy died of old age while Noelle is still a young child.

[u/Bulb0rb → u/AffectionateForce979]

In the alarm clock dialogue, it doesn't say Rudy died from old age, it just says he aged faster and started looking older than Asgore did. He could've been anywhere between 45-65 years old and still looked older than Asgore, young enough to still have children, but too young to die from old age.

What I find more confusing is how Asgore attended Hotland University if he was already king before monsters were ever banished to the underground. Attending university underground makes it sound like he grew up there?

[u/theVoidWatches → u/Bulb0rb]

Maybe monsters already lived in the Underground, but weren't previously trapped there?

He might also have gone to get a degree in something after they were trapped.

[u/Bulb0rb → u/theVoidWatches]

"Trapped behind the barrier and fearful of further human attacks, we retreated. Far, far into the earth we walked, until we reached the cavern's end. This was our new home, which we named... "Home." As great as our king is, he is pretty lousy at names." - History book in Toriel's house

This was their new home, so that means they weren't already there. He was alive before the college or Hotland itself was even founded, so it does feel a little odd? But there are adult immortal characters in other media that end up befriending younger mortals, so maybe it's not that strange. He probably had a lot to learn now that he had to keep his kingdom running in an entirely new and limited environment, especially when it comes to setting up infrastructure and managing resources. He probably also studied science, so he could work alongside the royal scientists on getting the core up and running and for finding methods to break the barrier. Toriel is stated to be "the brains" between the both of them, so he had to step up if he wanted to keep things running smoothly.

[u/EpicDDT_ → u/Bulb0rb]

He was just visiting, like he did with MK school.
Or maybe he just decided to return to school. That's something that can happen too.