Not just a reset. A RESET. An important word, underscored with an all-caps emphasis. Unique, detached from time, and a power privy only to an anomaly.

Or - two anomalies. Three, even, if his discussion with Asriel held any weight at all. The very same three who now live contentedly with Asgore.

So the doc nails it pretty much immediately.

"Depends on how much people remember." The course ain't necessarily always the same, no. But there are certain landmarks. Certain actions that always occur. "Once you gotta defined track, there's no reason it'd change, right? Not unless someone's able to remember. Not unless there's one variable effecting change."

And he circles the origin point.

"An anomaly."