First things first– Blueberry being trapped in the antivoid for so long would have made him an error. His official error design is here:
He’s just missing the errors, bcz I forgot to put them in, oops. Blueberror wouldn’t have been particularly DANGEROUS- not in the way Error is. A lot of an Error’s danger, comes from their final thoughts as non-errors. Blueberror’s final thoughts would not include ill will on others, so he’s less dangerous because of that. But he would definitely be, unhinged. Also, once someone becomes an error, they can’t turn back.
Error would have returned, to see Blueberry turned into– what we all sorta just called ‘Blueberror’.
Error would have actually been horrified by this- even if he didn’t show it outwardly. He wouldn’t have liked this outcome at ALL, promise you.
The main thing to note, is that Blueberror would have liked to make friends– and would have actually begun to socialize with those in the Omega Timeline (once he was deemed not threatening, but definitely kinda wacky).
In fact, Blueberror would have recognized he could not go back to his old timeline the way he is now, and would have literally given his world, to the other Blueberry that was in the Omega Timeline. So, the other Blueberry would have had a happy ending there.
Blueberror would have gone through all the stages– he would have been furious at Error, nearly trying to kill him- remember, errors aren’t rational, and behavior can be sporadic– but eventually, Blueberror would have come to a conclusion, that he would want to help those in the Omega Timeline, per Frisk’s permission.
Error Undyne would have become a massive issue– actually seeing Error in his glasses by accident sometime, gets her to irrationally believe, that those glasses belonged to Alphys. This would have sent Error Undyne into a murderous rage, becoming a genuine threat to EVERYONE.
I’ve always called Error a manbaby, because he IS a manbaby, and he’s a lot less threatening then he pretends to be– but Error Undyne is the real deal. SHE is an actual threat.
Blueberror is trying to hold on to what little sanity he has left, and try to convince Error to help stop Error Undyne.
Error would help, only because her existence pisses him off.
Long story short, everyone would have worked together in the Omega Timeline to stop Error Undyne (I can’t recall what I had planned in detail for Error Paps, sorry folks) and even though Blueberror gave up his own timeline to someone else, he actually finds a bit of a home in the Omega Timeline.
Error– doesn’t change at all. He helps them stop Error Undyne sure, but. Like I said, it’s because he didn’t like her. Shortly after she is stopped, and Blueberror is accepted into the Omega Timeline, Error just. Leaves- disappears.
This is actually pretty normal for Errors, tbh. They’re antisocial as heck and they just sorta- disappear all the time.
Also don’t worry! Blueberror is actually very happy helping out in the Omega Timeline. He has lots of friends there. He also got over his rage towards Error, recognizing that Blueberror’s anger was just poisoning him. He chose to forgive, and try and accept his new lot in life. I mean, Blueberror gets cool universe-bendy powers, so that’s neat. What are those powers exactly? Man I do not remember, but errors get cool powers. His power had something to do with stars…. dang. Sorry folks.
Remember– Blueberror is DEFINITELY messed up. He sorta develops this weird, half-innocent sense of humor– it’s kinda like he just stopped being on the same wavelength as everyone else, and would probably say things and make jokes that make people uncomfortable by accident. This was all planned a long time ago, so details have been forgotten. Lots of details, sorry!
But. Yeah to keep things short as POSSIBLE, this is essentially what was planned. There was gonna be big character arcs, big confrontations with some of the Omega people- huge timeline shenanigans, but. Truth is, once again a lot of the details have been lost. ;;; If there are contradictions, sorry it’s been a while.
(He genuinely doesn’t want u to be scared of him. He just looks a little spooky. Maybe don’t make that face, Blueberror.)
Error is actually Geno, after the events of Aftertale.
Geno is messing around with his determination powers, after Sans tells him not to mess with that. Geno does– and accidentally sends himself into the antivoid. In his last moments of sanity, he’s furious that he got his happy ending– and yet this happened to him. In that moment, he hated everyone and everything outside himself.
Good news- you can still enjoy the happy ending of Aftertale! Because Geno deserves that. You can also view it as- hey, there are tons of parallel timelines- so there will always be a happy Geno. Also more good news– Aftertale was concluded, and AskError was unable to be, so. Geno for sure got his happy ending anyway, and his sad ending was never truly written into existence.
Anyway. Sorry this was rushed. Yall deserved something sooner, and I tried to write up longer conclusions, including every character I was building up to in AskError, but. Frankly, I was just…. physically unable to. So, I hope this suffices somehow. ;;; sorry.