We all have seen Bell being travelled back in time, trying to fix things and such.
But this time, Aiz W. may even get the chance to turn back in time as well.
Do it however you want, make aiz op or whatever, maybe another aiz x bell fic, but Aiz as the protagonist.
This idea is mostly inspired by 'At War with Nature' by SackDantour.
I just want to see an Aiz time travel fic, really.
Though, it would be more interesting to see how she would react to see 'her' Bell, once again, after killing the minotaur that had been chasing Bell.
Bete can still be an asshole, but a respectable asshole. Maybe the time travelling Aiz can understand that.
Maybe take her to the point when she was born, when Albert and Aria is still with her.
Or when Aiz received her falna, as it resonate with the soul or something. This choice is recommended if you want to make an overpowered Aiz.
I hope this will make a good writing prompt, if it is a prompt at all.