I think the absolute saddest thing that I can think of for anything in the series, good end or bad end, is Sei finding Aoba in Clear’s bad end.
The obvious reason being guilt,
But the second reason is that his first instinct would probably be to fix it with scrap.
But Clear no longer has a truly human mind and can’t be scrapped.
So his only real hope after that is scrapping Aoba, to heal his mind.
He takes the blindfold off and realizes that that’s not possible either.
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And he knows that Aoba has voice scrap, so he’s holding him and begging him to use his power so that they can finally talk and everything can be fixed, but either Aoba’s vocal chords have already been taken away and he couldn’t even if he wanted to, or Aoba just can’t bring himself to do it.