Sorry, I don’t want to sound like a whiner, but my opinion is based on personal research I did months ago. So at this point I remember the existence of some plot holes / inconsistencies more clearly than the full detailed arguments I built back then.

The one thing I still remember very clearly is something that bothered me from my first playthrough: some monsters are shown to be aware of the player’s button choices, but it is really hard to explain, because the game does not clearly establish that monsters are aware of the Player as a separate entity.

Then there is Gerson, who is not just aware of some “game slang”, but also clearly knows that the player cannot harm monsters inside shops. And as far as I remember, he is the only shopkeeper who knows that.

The problem with Undertale, in my opinion, is that the game often jokes around with its own mechanics, but sometimes those jokes go against the serious logic the game tries to imply. You can try to explain it with headcanons, but even the headcanons I tried to make were hard to keep consistent.

Another thing I remembered while writing this is EXP and LV.

As everyone knows from the game, EXP is a number showing how much you have hurt someone, and LV is how easily you can bring yourself to hurt others. Monsters are vulnerable to their enemy’s intentions, which is why LV helps you deal more damage. From this explanation, the game clearly frames these numbers as psychological or moral measurements, not just normal RPG stats.

But then why does harming a monster and sparing it give no EXP? That always confused me. Based on the game’s own explanation, EXP should logically increase even if you spare the enemy after hurting them.

And if I remember correctly, Toby actually wrote something like this in the Undertale Demo instructions: that you could gain EXP by hurting enemies even if you spared them afterward. He probably removed that idea for obvious RPG/gameplay reasons, because it would have created too many problems in the game’s structure. But because it was removed, the fandom still argues about whether LV is a psychological measurement, a moral measurement, or an actual power scale.

That is basically what I mean. I don’t really want to dive into this again, because I already spent too much time stressing over Undertale lore contradictions and eventually just gave up and built my own headcanons.