The things from the OG multiverse (everything you know) that was not wanted did not die!

The only thing that happened was that they were sent to the void!

And those who were spared live in a purgatory,

And those deemed mistakes...

Met a fate much, much worse than death and were left with The failure.

The failure is what was left of Error sans after he mostly caused the end of the old multiverse.

What small amount of humanity he had left died.

The other being that lives there and gets no torture is what I'd call "Fannon Chara", and I mean the whole "Chara posses Frisk" misconception" a seperate entity than cannon Chara that lives in that purgatory

Also, the purgatory is a universe and die-hard UT fans might remember timeline