The 1st witch is a thing made by the world to balance it when some stupid civilization create a weapon that can nuke the whole planet.
The 1st witch success at destroying the dangerous civilization, but
since the world is stupid, it made a design flaw.
Ugh, this need a long explanation that related to Elrise, but trying to summarize it...
the magic on this world come from concentrated emotion of the people pemerating the air.
but the strongest emotion people have are MOSTLY the negative feeling, so...
When the 1st witch super buff herself with magic (alike to how Elrise do now), she is overwhelmed by the negative emotion of the people. She slowly become crazy because of it.
And since the world is stupid, instead of realizing it design flaw it decided to appoint the 1st witch's child for the next Balance method.
Aka the Saint.
And long story short, becayse the world force her, the child destroy her mother.
And her crazed mother almost killed her child.
But in the moment of clarity, she save her child and seal her away instead.
AND THEN because the world lost it 2nd balancer (1st saint), again, instead of working on fixing it design flaw, IT CREATES ANOTHER BALANCER (saint).
By this point the 1st witch already lost her soul and just a floating bunch of negative emotion. It parasitize the saints because it's instictually want to keep existing and the saints have similar property as them.
Btw, Elrise method of getting stronger is actually the same as the 1st witch, but she doesn't become crazy because...
....it's explained her heart is too black to care about negative emotion and actually thrives on it.
She actually get hurt when she absorb good emotion
yeah, positive emotion are actually as much as magic source as negative emotion. That's why I said Mostly at the beginning.
Also, it's implied the reason OG!Elrise is that much of a villain is because she have the same affliction as the witch, and she is also overwhelmed by the negative emotion.