im so excited to write this! no time to waste!
bill the summon a cage to keep dipper and mabel from escaping
"now it's just the 2 of us" bill said in a sinister tone
"well let's get started then shall we? how do i say this oh yea : it's not a beautiful day outside birds are running, flowers are dying on days like these doritos like you.." sans said closing his eyes
"should be burning in hell" sans said as his eyes go blank
"ha ha very funny" bill laughed "the let's go bonehead!" bill said preparing his blue fire
bill then grow 10 arms from him and start spamming them at sans
after a while he stop only to see sans is not there then appearing beside him
"what? you think i'm going to stand there and take it?" sans asked in a mocking tone dodging another attack by bill fire
bill then felt like a bone was throw to him from above
"hey" sans called from above him and disappearing with a gasterblaster behind him
bill with instinct step back from the blast area dodging it but he din't realise that behind him was a wall of bones bill then dematerialised and then materialised far from it
"this is the end of the world you know" bill said "you think you could still be a hero?" bill said turning red and started to summon bombs
"actually no i don't want to be a hero but i have a promise to keep" sans said dodging bill bombs
"well then you will die with that promise to your grave!" bill said firing a beam at sans
before he realise it bill was turned blue and being slammed to the walls and being blasted by gasterblaster
"go sans! woooooooo!" mabel cheered
sans just blinked as he cover himself in gasterblaster shell in order too block bill punch
sans then teleport infront him and telekinetically push him back to a wall
bill then turned red and then took part of the fearamid as his spears and throwing at them to sans
but all of them misses but bill was nowhere to be seen
sans then turn his eye on and looked around frantically
then he jumped as soon as bill hand come out of the ground below him
but then what he din't realise that bill was already behind him and then blast him with his blue fire
"sans!" mabel yelled
sans then lay there
"time for you to die!" bill said preparing a giant blue fire from his hand
but before he can sans then open his eye and slam bill to a wall of bones
"GET DUNKED ON" sans said as bill was slammed to the wall
"wow that skeleton is good" stan said from his cage
after a few while bill was tired which then give sans an opportunity to spawn a big bone under bill impaling him to the top of the fearamid sans then use his other hand to summon gasterblaster around bill and shoot them all at him
bill then flopped down who sans then slam
"you do know that i'm a being with infinite power right?" bill siad standing up
"i know that but that doesn't mean you can't be defeated right?" sans said shrugging
"what are you fighting for anyway? all your friends is dead what is left for you to fight? them?" bill said pointing at mabel and dipper
"i know you made all my friends disappear but everything they care about is why im here" sans said as he dodge bill hand slice attack
"i am their mercy" sans said slamming bill to a wall of bones
"i am their vegeance" sans said blasting bill with gasterblaster
"i am determination!" sans said as his bone stab bill
"ha! you are pa-" bill was cut when he suddenly feel something heavy on his back
"what?!" ford asked looking at a device from his pocket
"what is it?" stan asked
"bill power suddenly when drastically down!" ford said looking at the screen of the device
"what is this?" bill asked as he struggles to stand
"oh you feel it? it's you sin crawling on your back" sans said as he preparing something
"time to end this" sans said as sans begin to slam bill faster and then throw bill across the hallway with bones on the top and bottom of it when bill is at the end he was impaled by bones after bill manage to get out from the bones he was greeted by a ton of gasterblaster shooting at him continously for 10 minutes
bill now seem like a burned triangle impaled on bones
"take that you megalomaniac" sans mutters
"wow remind me not to mess with him" stan said
"sans i think you did it! you defeat bill!" ford said
"YAY! sans!" mabel cheered
"nice one sans!" dipper cheered
sans seem tired and fall to his knees and then giving the pine family a thumbs up
"hang on i'll get you guys out" sans said
"wait i though you say if bil is defeated this whole thing will go back to normal" stan said
"i'm sure it will be in a few moments" ford saidwhile they are celebrating ford device suddenly making a 'beep' sound quickly like a heartbeat monitor
ford look at the device and seem shocked
"sans! bill is still alive!" ford yelled
sans then look at the bone wall and then see bill is gone
as he turn around he saw bill slicing him with his blue flame
"ha ha ha you think you can beat me?" bill asked
sans then trip and begin to bleed on his wound
"SANS!" mabel yelled
"now where was i? oh yea killing you . shooting star" bill said grabbing mabel
"let her go!" dipper demanded
bill then charge up a beam aiming at mabel in his hand
"wait!" sans said getting up
"oh any last word sans?" bill asked in a snister tone
"you remember what i said earlier?" sans said grabbing a purple gem from his pocket
"if you touch hurt those kids..." sans said
sans then break the gem and darkness starting to surround him
"you be dead where you stand" sans said as the whole darkness grow around him and become a dome like figure
"exactly where you stand!" sans yelled in a demonic voice
after the darkness fade sans was different
this time sans head is big with 2 hands,gasterblaster as his shoulder and no bodies. both of his eyes is shining one is blue and one is orange
ULTRA SANS (to summarize it XD)
"get comfortable" sans said
bill then seem to be afraid for once
"huh though i will never see bill scared" ford said
ford device then suddenly beeping faster and louder
"IMPOSSIBLE!" ford said looking at his device
"what is it?" stan said
"sans power... it's beyond bill power!" ford said
"i though you say bill power is infinite" stan said
"i don't know. it might be broken or worse but bill expression completely say that this device is right " ford said
"ha ha ha hahhahahahaha did you really think you can stop me?" bill said nervously putting mabel back to the cage
bill then shoot a big beam at sans
sans then open his beam from his hand and easily overpower bill beam
bill then throw a some boulders at him but sans then reverse the boulder
"uh uhh henchmaniacs!" bill called
soon all of the henchmaniac come to bill
then they all charge at sans
but sans just open his arm and shoot his beam at them disintegrate them
"you won't be spared" sans said
then a giant hand then come out of the ground below bill trapping him
bill then struggle to get out from the hand
"trust me..." sans said
"you're going to have a good time!" sans said preparing to shoot his beam at bill who was still struggling
"please let me go!. i promise i won't come back i swear!" bill pleaded
"sorry ran out of mercy" sans said as he shoot his beam
"NOOOOOOOOO" bill screamed in a demonic voice
then suddenly a wave of energy rush over gravity falls pulling all the weirdness back to the rift
former fearamid site
everyone was standing there and sans was there on his knees
"sans! you did it!" mabel said running to hug him
sans then stand up
"nice one sans" undyne said
but then everybody expression change except the pines family and mabel who was hugging sans
"what's with the long face?" mabel asked
mabel then step back and see dust starting to come out from sans
"sans?" dipper asked
"kid." undyne said grabbing mabel shoulder
"what's happening to sans?!" mabel asked
"when a monster dying they turn into dust" alphys said
"you mean?!" mabel said running to sans and hugging him tighter
"dunkle sans please don't go!" mabel said as tears started forming in her eyes
"i lost papyrus i can't lost you too!" she added
"kids. listen" sans said getting dipper and mabel attention
"please don't be sad i know it's hard to say goodbye but papyrus always said 'if you remember someone they don't die. they just gone forever'" sans said putting his hands on mabel and dipper shoulder
"and you know what? i have no regret of d-d-dying. i have live quiet a life i have f-f-friends,a g-g-good brother and the best a-a-adventure of my life" sans said
"i think it's the right time to close my book" sans said closing his eye
"but i w-will tell ya something: you two are the best s-s-siblings i have ever encounter"sans said grinning making dipper and mabel smile
"so i guess this is the time to say goodbye?" sans said offering the twins a hug
the twins hug sans as he dissolve into dust after he dissolve into dust and a reverse heart come out of the dust cracked then destroy to pieces
stan then pull off his fez in order to honor him
"he sacrifice his life to save us? he really is a hero" ford said
"all this time i though he was nothing but a bone bag" wendy said
"he was the coolest dude i have ever meet" soos said
all of what's left of sans was papyrus scarf and his jacket
"i think he want you two to wear it " undyne said giving sans jacket and papyrus scarf to them
mabel then grab the scarf and dipper wear the jacket
"hey don't be sad sans said it himself that he don't want you two to be sad" toriel said
"y-yea cmon let's go meet the other" undyne said
then they go back to the others by the shacktron
"where's sans?" gaster asked
then he see the twins wearing their signature clothes
"oh i see he must used the gem" gaster said
"how do you know?" mabel asked
"sans always have that gem. that gem is a part of the royal crystal of the underground you see that crystal powers the entire underground it's power is immeasurable but monster soul can't take the power instantly died after using it. i impress how sans can take the power that long i dont know what make him can withstand it" gaster explained
"and why do i did not know of this?" asgore asked
"we don't want it to fall into the wrong hand" gaster said
mabel then look around and saw flowey returned to normal with 5 souls on the ground circling him
"flowey are you okay?" mabel ran up to him
"heh at least i help you guys" flowey said
just as he said that he suddenly smoking
"wh-what?" flowey asked as he fly to the sky and then turned into a goat like kid with a striped shirt
"i-i'm back!" asriel yelled
"but im falling!"asriel yelled
he fall down to dipper and mabel
"so this is how you look like before you become a flower" dipper said
"ha ha yea" asriel said
"asriel?" asgore asked
"mom! dad!" asriel said running to them
"my son!" toriel said in joy hugging asriel
"i though we lost you!" asgore said
"look like the souls decide to give you some of their power to you" gaster said
"maybe because i do a good thing for once" asriel said while being pat by toriel
"hey are they still going to be a birthday party?" grenda asked
"heck yea!" undyne said
"but how do we move the shack back?" stan asked
"leave that to me" gaster said lifting the shack telekinetically
"ok then" ford said
whew finally finished it well time for the epilogue and as i said before i will make 1 bonus chap after the epilogue