Mirrored Insanity

Story
Dust!Sans was doing his own business, When suddenly, A different skeleton appears in his way, And he's covered in darkness, This skeleton just happens to be Insanity Sans, Who has arrived in the DUSTTALE universe due to an unknown glitch in the multiverse, And because it's so empty in the DUSTTALE universe, Just like it is in Insanity Sans's universe, Insanity Sans doesn't notice that anything's different. Dust!Sans feels like he's looking at himself, Which he technically is, Therefore he asks this stranger "Why do you look familiar?", Usually, Insanity Sans attacks everything without a second thought, Bugs, Insects, Any moving objects, And even sound, But the creator forgot about this, So he kinda got Insanity Sans wrong in this AU, But Insanity Sans replies with sinister laughter, And then replies with "Why?" "Well...Let's just say that..." as this sentence goes on, The darkness surrounding Insanity Sans fades away, Revealing his true colors, Showing himself as a Mirrored Insanity, He then finishes his sentence with "I'M THE MANIAC YOU SHOULD RUN FROM =)", And thus, The first battle begins.

PHASE 1

Dust!Sans has no idea what Insanity Sans is capable of, So Dust!Sans assumes this is just some other weakling standing in his way, Little did he know, He was all wrong, Insanity Sans shows no mercy, And ends up killing Dust!Sans, And Insanity Sans watches Dust!Sans turn into dust, And as he does this, He accidentally absorbs a small fraction of Dust!Sans's determination from his soul. Insanity Sans has won, Or so he thinks. Insanity Sans looks at the dust pile and says to himself "Heh..." "That guy actually put up a good fight..." "A shame he didn't manage to hit me...", After he says this, He turns around, Ready to leave, But as he does so, He hears laughter from the pile of dust, As this happens, The pile of dust starts to glow red, And then the dust reforms itself back into Dust!Sans, Dust!Sans used most of his determination to resist death, Which explains why his eyes have turned red and purple. Insanity Sans turns around again, Facing Dust!Sans again, And Dust!Sans then says "You seriously thought it'd be that easy to kill me?" "I'VE ONLY JUST GOTTEN STARTED", And thus, The second fight begins.

PHASE 2

Dust!Sans now knows that Insanity Sans is a huge threat to the entire universe, And he has to put an end to this monstrosity, Dust!Sans is not holding back anything now, And does everything he can to eradicate this maniac entirely, Insanity Sans can't keep up with this insane amount of power that Dust!Sans is showing, And therefore ends up getting killed, Dust!Sans is victorious. Dust!Sans is relieved that he's stopped this insane creature for good, "Finally" "That insane freak's dead", He says with relief, But it's instantly replaced with fear as he notices that he's not getting any LV, "But...Why didn't i gain anything from it..?" He says, Suddenly, He sees Insanity Sans's soul come out of the dust pile, And he notices that it's red, And he instantly knows what that means, With fear he says "Wait what the!". And thus, The finale begins.

PHASE 3

Dust!Sans watches Insanity Sans's soul reform it's body, And Dust!Sans gets ready, At this point he's terrified, Since this insane maniac now possesses a small fraction of determination that was absorbed from Dust!Sans. After Insanity Sans's body has reformed, The two ready themselves for a few seconds, And then suddenly, They both launch at each other with great speed and power, Cracking the ground they were standing on, Both are now using all of their power against each other, But after an incredibly long and intense fight, They end up killing each other with their special attacks, And just as we think they're both about to die, Dust!Sans grabs Insanity Sans's soul and absorbs all the power and LV from it, Giving him an incredible amount of power, This also gives him even more determination, Which allows him to yet again reform himself into his body, And resist death once again, Dust!Sans is victorious, And Insanity Sans is brought down for good...

Bonus Story
After Dust!Sans has killed Insanity Sans for good, goes back to the ruins to face the player (AKA Frisk/Chara) and because of the insane amount of power he now has, He ends up being victorious against the player, He gains the players powers, And resets the world, Removing Frisk and Chara from the universe for good. Dust!Sans has now gotten his happy ending he was seeking for, But the hell he had to go through, Still haunts him 'till this day...

THE END..?

This whole text was written by ReveX himself, If you don't believe me, Ask him yourself on discord or something.