My current understanding from reading between the lines is that Othinus actually succeeded in killing herself, and thus Touma would doubt himself and head down a different path.
>Did it count as saving someone as long as they were smiling? Could an action that went against someone’s wishes be called saving them?
>“Maybe I was too presumptuous to think I could save someone.”
However, this derivation from his normal path seems to go against the super magic gods plans. To prevent this they fixed up Ollerus into her 15cm form.
>“We have no more attachment to Othinus herself, but this ending could hinder Kamijou Touma’s future. Then again, I doubt anyone but us could resolve this now that a magic god is involved. It would be a shame to have the direction thrown off so much for something so trivial.”
>“Most definitely, Nephthys. The High Priest has just corrected the disorder caused by Othinus. From here on, Gremlin will show its true value.”
>(But would my body “automatically” re-form with no intervention from my will? I still have my questions about that.)
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The real gremlin seems to be an abstract organization of magical gods. And it seems Othinus is a latecomer that never actually made it to the party.
>“Gremlin, the name of a plain fairy that is not dyed in the colors of any existing religion.”
>“Instead of being a fusion of science and magic, it’s an organization that every magic god of every religion can take part in equally☆”
I have my questions about whether the space they were residing in was a place of existence one or many dimensions higher, which is why it was not destroyed my Othinus, or whether it's some silly tricky bullshit like also inside of Touma's hand. Speaking of which we still aren't any closer to knowing what his hand actually is. Fiamma of the right figured it out, and was killed by Aleister in part due to that. The only thing we were able to learn from him, iirc, was that IB could be used as a ranged attack.