(Answering to this)
That's weird... What if the costant Resets are the reason why the player isn't showing up?
Wait- do you want the player to show up at all? Is it a good or a bad thing if they come back?
Let me in on a secret Asriel control the Reset Button he now control the AU he knows about alot of stuff that you don't even know, and moor sure he has the means to reset save by the fact he has chara's soul.
and the constant resets are just making new timelines without anyone realizing a reset is just another timeloop but moor complex right? but what if you did something different in that timeloop and there's the save feature it means whatever happened in that time you can save even if you reset you can go back to that time then keep people mind in the blink
A monster normal don't understand that concept But a player normally use a save point to save progress but a monster useing it can do anything like when a monster resets its like going back in time and they can try to " fix " things they don't like in there eyes but using a save point it's like saving place in time even if you reset that one moment in time is still in the save point so that monster can send all the memories from that save point to the reset and then make it seems like they are doing something good
But if that monster go deeper like look I in the file's like the player would do they can completely rewrite everything into what they want make them believe anything while erasing there true memories
The player would just normal follow a set of rules they are given to go through the would while the monster who's apart of the world can do so much moor with the power of the player
Unless there's any safety checks there's no way to stop a monster with the power of the player