(MC POV)
After my apparent 'loss' in the war against the Great Ones, most of my Origin essence was left behind in the centre of the universe.
I then went and reincarnated myself in the mortal worlds, living amongst them as one of their own and just generally experiencing living as a mortal.
I managed to get through a few lifetimes normally before Iris finally found me.
The mortal me had slowly gained empathy over the years and she had found that to be abhorrent, thus the formation of her plan to 'reset' me back to how I was before.
Since her power of creation was limited and her forte laid in Ending things, she couldn't just 'make' me apathetic again.
Sure, she could End my feelings, but having no emotions is not the same thing. And it wasn't like the past me had no feelings either since I did love everything equally.
Thus, she used her omniscience to find the best future that she could influence to return me back to how I was before.
