Oneshot book

The 'Fallen Guardians'

Error had jumped into the void.
After being ambushed by an incredible high amount of sans, Error went to outertale to end it all, followed by all the blind judges to the cliff where the black boned skeleton loved to stargaze.
Realization hit them too late, Error was already far below in the void when they understood his last words. 

"AfTEr AlL iT's OnLY wHeN SOmEthInG Is MisSInG ThaT YoU ReAlIZe HoW ImPOrTAnT It IS"

After that ink created non-stop for days, blocking the access to the doodle sphere so no one could disturb him in his 'work'.

But by that he only accelerated the fall of the multiverse. 

-years later-

The multivers was in ruins. With only some universes left floating in the vast white space of the doodle sphere , the place devoid of any living being. Ink had disappeared and Dream was left to deal with all the negativity that was produced by the monsters left in the omega timeline. The nightmare gang had disappeared too, staying hidden in their castle after the suicide of Error. Only some monsters were left spared of this disaster , because if a universe didn't die to the void, it was left to crumble and fall in ruin like ,Blue said, in some apocalypse movies.  

In the town of ebbot city , you could if you squinted you eyes enough see in the background a group of monster walking in the dust that was covering the ground of the city. Those monsters were called the 'Fallen guardians' a group of people that explored what was left of the multiverse in hope of finding more survivors in those desolated place. The group was composed of UT!Undyne, US!Toriel, OT!Chara and Crow (birdtale sans), Crow having lost his whole Au and Cosmo only having her Gaster and Papyrus left and of course her Sans.

"Are you sure that we are going to find someone here ? this place is dead . . ."

"Thanks for the reminder Cosmo" Undyne told , head down in a frown while eyeing suspiciously the place, head bouncing from right to left in hope of catching any movement.

"Dear, can you two stop being unpleasant for a minute ?"

"Well Cosmo s'not wrong Tori, we were walking for Asgore knows how long and we haven't seen a single soul"

Silence fell on the group when they came face to face with an amalgamate in the middle of the road in the giant city. The being was staring at them with his multiple melting eyes with a look that was just screaming one single thing "food".
Undyne, in a hurry, spawned a spear in her hand and started slowly approaching the melting monstrosity while Tori kept her guard up, trident in paw to protect the other of the possible threat, Crow giving her that one look of 'seriously ? i don't need your protection ya know'.
Undyne stopped herself when the amalgamate launched itself in the air with the goal of landing on the royal guard who swiftly moved to the left all the while throwing a large amount of spear on the amalgamate. The said creature roared in rage as it tried to land a hit with their paw-feet whatever it is on Undyne, who just kept dodging and attacking. Meanwhile the three other members of the group watched with little interest the fight, Crow having fallen asleep next to Tori who was trying to stop Cosmo from joining the fight. A paw firmly on the head of said child , holding them in place.

Undyne jumped out of the way in time for the amalgamate to come face first with the wall of a building, the ground shaking from the impact which was enough to wake up Crow from is slumber. The said feathered sans shot a bone in the supposed head of the beast to neutralize it for a while, the amalgamate being sort of un-killable because of the DT they've been injected.  

"FUHUHU GOTCH'A" 

"'Dyne we need to leave , i have a bad feeling." Crow said , worry evident on his features for some unknown reason to the group.

"Yeah anyway there is nothing here come on we need to go !"

Right on clue the ground started shaking violently, the road fracturing itself at every corner. The universe was dying. 

"OH SH*T" 

"LANGUAGE UNDYNE !" 

Cosmo quickly took out a device from their pocket to teleport the group in a safe place before the void caught them in its deadly trap. Tapping on the multiple buttons like an expert, the device finally opening a portal for them to escape trough.

"Well we lost the original SwapFell"

"Did we had any monster coming from here anyway ?" Undyne asked while looking for a place to take a break. 

"Hum pretty sure that we had the Frisk from this universe back home along with Smoke and some other monsters  .." Crow said, looking down at the ground with a pale face.

"Another one gone, how long are we gonna be able to keep this up ?"

"Dunno Tori, dunno."

If you were asking what was the dumbest rule in the multiverse right now, they would have answered you with the fact that when a universe die, only the sans counterpart is capable of surviving the fall of their home, and when a sans counterpart dies, his universe fall with them. A stupid rule you can say, proof being that they had lost many because of it. Right now the group was on a cliff in the original underswap, the sun not even visible with all the clouds present in the sky, hiding the only source of light beside the town down below. Underswap was the only universe along with Outertale that was still in 'normal condition', all the monsters and humans still alive here even with all the recent events.

At first they were 6 and not 4 in their little group. This week they had lost AlterTale Papyrus, his universe had died while they were on a mission to find Antivirus who had previously disappeared from the gang, nevertheless universe kept falling in the void even when not so many of them where left. 
The group then prepared a fire, Cosmo munching on marshmallows that somehow got here, perhaps from their inventory, whilst two other skeleton approached their little camp witha steady pace.

"COSMO, TORI, UNDYNE IT IS ME THE MAGNIFICIENT SANS HOW WAS THE EXPEDITION ?"

"sup"

The group who was now facing the swap skelebros started to explains the loss of yet another universe. Blue didn't need to show his sadness for the other to get the message, they all knew how it felt after all, losing a home even if it wasn't their, each universe were similar enough for it to leave a weird feeling of loss. Stretch had an emotionless face as always, smoking another one of those cigarette that Blue hated with all his soul. Toriel watching as the two skeletons that were previously filled with life sat against a tree bark in silence, Blue opening his arms inviting Cosmo to join him in a cuddle pile. To say that everyone was sad with the 'end of the world' was an understatement, everyone was either depressed or totally breaking down from the loss of their family, and the two skeleton brothers weren't an exception.

Undyne watched the fire burn the last leaves that were thrown into it earlier, a frown adorning her features remembering how she, herself, had lost Alphys on a mission at the start of the collapsing.
Crow who went searching for more wood to add to the fire came back holding some branches humming His theme before stopping himself at the view before him. 

"hum am i interrupting something ?"

"yes, yes you are Crow" Undyne said, glaring at him.

"hum well in  that case i can go back in the -"

"just shut up for ounce"

"Undyne please this is not the moment for that" Tori was now looking very annoyed by the situation. 

Cosmo, still in the skeleton cuddle pile had a little smile on their face. Stretch was fast asleep as Blue watched the members of the so said guardians arguing for no reason , the fire camp in the center of their little friend group lighting the scene up. All of them were going though times in a way or another, even so, they kept fighting for their hopes and dreams,  while discretely being watched by another being.

Thanks for reading :D 
I got the idea last night while trying to sleep and i really wanted to test my writing skills so here we are :3 
Don't expect this book to be often updated , because i'm really lazy and my motivation is not something often here (they went to buy milk a while ago now ;-;)

Edited on 25/11/23

part 2 ?