A/N: This is the final chapter for this story. I completely lost motivation for this and everything else due to personal things but I didn't wanna be the person that leaves a story abandoned, I wanted to end it at least somehow. Thank you to everyone that has been reading so far (and thanks to the people that have binge-read the entire thing, props to you). 18 chapters was almost 3x longer than I wanted it to be but here we are. I'll still be making other stories in the future for Undertale, just this one is drawing to a close. Thanks to Yours the Author for betaing!

"If you do so, I will devote every remaining waking moment of my 'life' to hunting you down."

At that response, Sans glanced up at him, almost unsure if his friend had even caught his joke; he was a very a literal person. But there was a small glint of hidden spirit in his eye, and Sans knew Gaster's reply was all in jest.

"alright, fine then," Sans sighed, standing up from the chair despite not being entirely sure where to start heading off to, "to the void we go."

oh boy, am i dreaming?

"I am here. Where are you? I know you are here too," the Gaster that Sans had come to know announced his arrival, inconspicuously standing several metres in front of him in a shielding-like stance. Alphys and Frisk trailed behind Sans, on guard and tense from emptiness of the void around them.

no, actually, i'm having a nightmare.

A dark fuzzy figure fizzled into so-called 'existence'. It was obvious who was under the cloak, fractures spread throughout the skull. No description could fit the creature; it had no form or sense of being. Yet it was obvious to Sans who it was. Sans idly grabbed his blue jacket for comfort, which felt oddly like a whole lot of nothing.

The group stared onwards, panicked at the dark form that approached them, their restlessness emanating in the empty void. It was their Gaster from this timeline. He, who had been trying so hard to return to the mortal realm in his own respective timeline. And now they all stood willingly in front of him.

"I spend an eternity attempting to return to my time, and now you are all here standing before me. If I had known, I would have tampered with Frisk's mind much sooner," frenzied eyes drilled into the child in question, but hers in contrast were brimming with determination.

Sans' stomach dropped in the same way it did whenever he came across Frisk for the first time in each genocidal run. Somehow, in each specific reset, he always knew with each return if she came with the intent to kill everyone. Alternatively, he also knew when she had returned to be a pacifist. He had the former feeling with Gaster now.

"B-but, I don't understand…I…Gaster…" Alphys looked to be content cowering behind the other Gaster, who had been remarkably quiet since arriving. "We worked so w-well together, in the lab. And with Sans, too…why are you like this now?"

"because he doesn't have a soul."

All heads turned to Sans, surprised at his sudden exclamation.

He shrugged half-heartedly, "what? i'm being literal. he doesn't have a soul here. this one does," he prodded the other Gaster in the back, and in exchange received a slight scowl.

The void-Gaster didn't respond, and simply pulled down the hood of his cloak, aware of the others watching him intensely. There was a spark in Sans' soul waiting to kick into life at the very smallest of signs that this monster was going to pose a threat to any of his friends here. He silently thanked the stars that Papyrus wasn't here.

"What is it that you want? Why are you here?" the creature asked instead, turning his head in unnatural angles. Frisk was cringing at the sight.

"I know what you are doing to the child, Asriel. His soul is infected, and you are waiting to claim it as your own so you can return," the other Gaster acknowledged, inching away from Alphys who was pressing closer and closer into his side.

"You all think you are so smart." The void-Gaster countered, taking a step closer to them in what could only be assumed was an intimidation move.

The Gaster with a soul chuckled darkly but didn't retaliate, "We are the same person."

"B-but, this is wrong," Alphys spoke up from behind them, visibly trying to pull herself together and failing with shuddering breaths, "Asriel has j-just came back to us. You would do an irreparable amount of damage to the king and queen, not to mention taking an innocent soul to save yourself and hurting m-many others," she sharply drew in a breath to collect herself.

yeah, go on, Alph.

Void-Gaster snorted, "A bold claim for you of all people to say, Alphys."

Alphys paled, if that was even biologically possible, and withdrew from the 'conversation'. She backed away behind Sans. Frisk, who seemed to be the least afraid of the mortal bunch, tried to innocently smile to help cheer her up. Of course, considering what she had seen in Alphys' true lab, it would be hard to find anything worse to scare her.

"I could just take your soul," void-Gaster addressed to the other Gaster, sizing him up despite being the same person.

"Then the cycle would continue, and I would end up like you."

"A worthy sacrifice, is it not?"

"Clearly, we do not share the same thoughts."

"Evidently."

this conversation is the most pointless waste of time i've ever witnessed.

barring the resets.

Sans cut in, "well, isn't this just the most riveting of hangouts."

Both Gasters turned to him with identical scowls set upon their faces. The sight was almost amusing.

"what? if I were stood here having a conversation with myself you'd be bored senseless too."

He was feeling rather confident despite facing certain death.

Two of them.

To his surprise, void-Gaster disappeared in front of his eyes and reappeared behind himself and Frisk.

Sans tried to call upon his magic instinctively to protect himself, but the blue light simply fizzled out.

His eyes focused on void-Gaster, whom had an amused expression upon his twisted face.

oh boy.

"That will not work. You have no power in the void. It is mine to do with as I please."

Sans narrowed his empty eye sockets, "so you own the void."

"Yes."

"nice. sounds like you should stay here then."

"You and I both know that will not happen."

oh well, worth a try.

The other Gaster held a dark, silent expression that even Sans couldn't decipher.

What does he know that everyone else didn't?

He tried to come up with theories.

He needed a soul to make it back to the real world. That's how Chara returned after all.

...wait a sec…

"hey, G," he stopped staring into space (or the void), suddenly brimming with ideas. Both Gaster's turned to look at him.

oh, yeah. two of em.

"not, you, the weird one. droopy face."

'Droopy Face' lifted an arm presumably to send Sans zooming ninety degrees upwards into oblivion, so the smaller skeleton spoke quickly to avoid such a fate.

"what did you do to Chara?"

Aforementioned armed dropped.

that hit a nerve.

"What do you know of the child?"

"i know that you had something to do with her possessing my pal here," he swiftly grappled Frisk into a protective embrace, causing a squeak.

"She needed a soul. I gave her one."

"yeah, no. you weren't being kind, were you?" he watched void-Gaster face contort into mild panic, which quickly twisted into a smirk. Clearly he was on the right track.

"What makes you say that?"

"you used her as a guinea pig, didn't ya? you had the ability to pull Frisk to the void, so I assume you would be able to pull Chara back into the void once she had a soul. so then i'd guess that you'd kill her and take it."

"Clever." The smirk contorted wildly, the grin almost stretching to the cracks at the top of his head. "Very clever."

Frisk visibly cringed at that, recognition dawning on her face. Weird.

"It is true, I can only bring humans into the void, and since finding myself here no human has fell down, until Frisk."

"so you tried to get Chara to take Frisk's soul."

"Indeed. She was…exorcised before I could bring her to me."

Sans sighed, running an exasperated hand across his face. All of this just so Gaster could come back to the living realm? Merging timelines, Chara almost returning, Frisk's powers and nearly dying, him nearly dying, just so that he could come back?

"But now, here you all are, standing before me. Four souls to choose from. If anything else, it seems I got your attention."

"frisk has magic," Sans emphasized, pulling the kid a little closer, "that was you too, right? that was…." he breathed, thoughts dawning upon him, "Chara didn't work, so you used frisk to bring us to you."

Void-Gaster eyed Frisk intently, as if analysing her for the truth. Then, he grinned. "This was not of my creation."

Sans blinked.

"what?"

"I did not give her magic."

"you…" how? "how did she get it then?"

He nearly jumped at the sound of someone clearing their throat behind him. Sans quickly turned, almost forgetting Alphys was here. "Erm…like I've said before, sharing a soul with Asriel caused her to get it by chance. I…I think it's plausible that G-Gaster didn't have anything to do with it."

huh.

"right." it seemed odd not to blame Gaster for something as obscure and unusual as this, especially given his knowledge in the field. Human magic was unheard of, and Frisk was the first one to get it.

"ok, well, guess I believe you, for some reason,"

Well, he had all the answers now, everything had been lain out in front of him. But there was still a problem.

He turned to his friends, "well this is good to know and all, but the hell are we gonna do about him?"

"Um…" Alphys wrung her hands together, "We could…leave him here…?" her face was so contorted with worry that it was obvious she didn't even agree with herself.

"No, that cannot happen," other-Gaster denied, finally speaking up after standing in contemplative silence for so long. Who knows what he had been thinking. "That is not how this ends." The white glow of a monster soul unexpectedly materialised, floating freely in his hands.

The lights in Sans' eyes went out.

what?

Sans was both furious and scared, "the hell do you mean, how this ends?" the sinister grin on void-Gaster's face was inexplicably fading.

"When I looked into Frisk's head, I saw what she saw. This does not end here. We cannot leave him here; it is too dangerous."

The grip on Frisk dropped, Sans stared at her in disappointment more than anything, "you knew this, and you didn't tell me?"

"I didn't wanna worry you," she whispered, her brown eyes huge, "I know how you get."

The Void-Gaster remained silent, clearly understanding what was happening.

"you," Sans jabbed an accusing finger in his direction, "don't you have anything to say about this?"

The distorted grin had melted back into an almost-normal expression. "This…outcome, was not of my doing. I was not anticipating this."

"We have to," a soft voice from Frisk stated, "I've seen what will happen if we leave him here. He eventually has enough control over the void to bring humans from the surface here. And now that the barrier is broken…he will take thousands. And…I've seen…things…" she swallowed, gaze dropping to the floor, "From Asriel…I've seen things…and that was just monster souls of the underground…and Gaster…if he could take human souls of even one city…"

Sans, in one great breath, spun around and grabbed the hinges of other-Gaster's cloak furiously, "you can't damn well bloody kill yourself for this freak!" he whispered harshly, "this…this bastard is not a replacement for you! you are not dying to save him!"

"Sans." The deep voice demanded, though with a slight hint of sadness, "Do you really still not understand?"

Arms flew around the air in anger; it was lucky he didn't have a soul in hand, "no I don't bloody well understand! did Chara put you up to this? i thought you were different than him, g, I thought…"

"Sans—"

"you were just like the gaster that I knew—you're like this Gaster, my Gaster before the void screwed him up. you were like him. and when I was just getting used to having you back, just starting to trust you again…you do this. you sacrifice the yourself for this maniac!"

"Sans!" Gaster repeated firmly, causing the younger skeleton to stop shouting. "I am him!"

Silence deafened the void.

"…what?"

Sans subtly tried to glance up to the void-Gaster, but again he only stood there, his expression grave. Clearly he had caught onto the situation.

"This was always going to happen."

Sans nearly, choked. "what. what are you talking about?"

"I am not from another timeline. That is what we all had assumed, including me. But the abnormal readings from me was not from a different timeline, but from a different time. Hence the readings."

His eyes were still blank, "i still don't understand."

Gaster sighed but explained in a hushed tone. "The 'maniac', as you so call it, Gaster, that stands before you right now is me. In the past. I gave him my soul and he becomes me."

The lights in Sans' returned, although small. If he had any internal organs, they would probably have imploded by now.

"but how come you didn't remember? surely you'd remember being him? this conversation right now? aren't your memories intact?"

Gaster shook his head, "Gaster merged the timelines with the attempt to free himself but by doing so he has created a paradox, and that paradox is me. It always has been. Once we leave the void, I will cease to exist, and all memories of the void will be wiped from this Gaster before you. He becomes me. And the paradox closes."

This would explain why Sans had such a heavy reaction to the timeline merge in the first place. Not only his sensitivity to the timelines, but the paradox, which was Gaster. And he was Gaster's creation. His…son.

Sans glanced past him, eying the deranged, crazy killer that stood 5 feet away. "but he's a psychopath. he's not you. you're not…" he took a breath, "you're not him."

Gaster offered a genuine smile, "I can assume you, I am. We are the same being, the same person. From the same timeline. He is from the present; I am from the future. I suppose I am proof that he…" he paused, "I, can still be saved."

Hesitantly, Sans turned towards Frisk, who was gazing up at him with a sincere expression upon her face. She was determined to save someone. And so he knew what Gaster was saying was true.

"you had better be right about this," he muttered, releasing his grip and taking a step back. "if you're messing with me or this goes wrong, i'm gonna…" he paused and emptied his sockets to prove a point, "i'll make sure you'll have no choice but to reset."

Frisk grew wide-eyed, creating distance between them but shaking her head, "I'm not messing with you, I promise."

The lights returned. "hmm."

After a beat of silence, Gaster cautiously stepped across from Sans and approached the void-Gaster.

"I believe this is yours," he announced, a white, slightly cracked soul floated above his hands.

Surprise spread across the void-Gaster's fractured face. Decades in the void must have made such a turn of events surprising to him. Being offered a way out, despite everything he did to get himself out. Something he didn't anticipate.

But to everyone else, they were just glad he had stopped making such creepy expressions.

Gaster took the soul and observed it curiously. It glowed brightly, as if the entity itself was alive and craved to be reunited with its owner.

"Curious little thing," he muttered, allowing it to engulf him in a beam of light. In a haze, the cracks slowly mended as the evidence of his time in the void sealed together, although still were visible as little chipped pieces on the top of his head.

When the light eventually dissipated, he glanced up; the other Gaster was suddenly gone.

The concern faded almost as quickly, and he was left with an empty feeling, as if he had forgotten something.

Looking down upon himself, Gaster found himself noticing his newly repaired physical form…and a large gap in his memory.

"Hmm."

He had a few seconds to take in the shocked faces of the three friends huddled together, before all energy zapped from his body. His vision faded to black.

...

The next time Gaster awoke, it felt like hours had passed.

No, days.

Such a loss of time sense was unusual and quite frankly disturbing, although he had no intention to show that.

Opening his eyes, he struggled to remember the events of before.

Where am I?

What day is this? What month?

A hand clasped onto the window ledge, and he pulled himself upright, desperate, no, impatient, to look out the window.

He expected to see a blanket of snow and the familiar sparkle of Christmas lights, however…he saw only green.

Green.

Green, and tall, tall buildings…

…What…?

"What in the world…"

As he spoke, he heard the telling sudden shuffle from behind him, whizzing around to see who else was in the room with him. He had been so desperate…impatient to find where he was that he didn't think to see what house he was in.

Muscle memory was obviously at play here considering he successfully made for the window; it looked like the skelebros house except the surroundings were somewhere entirely different.

Focus.

Forcing himself to concentrate, he noticed Sans.

Sans.

Why did that name cause such…an empty feeling. A sinking feeling in his gut?

If he had one.

There must be a reason for it, because the young skeleton was staring right through him, sitting idly in the corner as if he were asleep with his eyes open.

"Sans," he finally spoke the name, still not sure of the negative association that came with it, "Where are we?"

Sans snorted, shutting his eyes for a moment and taking a deep breath.

Really? It's this much of a long story? Why not give a straight answer?

"you really don't remember, huh."

Gaster narrowed his eyes, "If I remembered, I would not ask."

"well," Sans paused, his eyes darting around to random points of the room, obviously anxious for some reason, "well…pal, bucko, my good ol' buddy chum, friend…dad."

"Answer the question."

"on the surface."

Gaster wasn't sure of the feeling he was feeling but it wasn't entirely negative. Still, all he could manage was a simple: "What?"

Sans leaned back into the chair and closed his eyes at that bombshell of information, "eeyep."

Gaster would have completely torn down that statement and pinned it as a lie, but quite frankly the evidence was there. There was only green outside. The buildings were similar to those from the surface, if not the same. Perhaps this was a sick joke, which was extremely unlikely given the memory loss. It probably had something to do with that, instead.

"How did…" he paused and cleared his throat, trying to pass off the feeling of his throat closing up as a minor inconvenience with a sudden cough. "Apologies. I appear to have a lapse in my memory. I will have to look into this."

"i know."

So, Sans did know about this. Still, it was very unlikely this was all a joke. As much as a comedian Sans tries to be, he definitely would not pull off something like this, especially to his own family.

"Was there an accident?" he tried to reason with himself more than anything, "Something that would cause temporary amnesia, perhaps?"

He was growing impatient. Less with Sans, more with the situation itself. And the cracks were starting to seep through.

Cracks…

Why did that phrase trigger something within him?

"i guess you could say that," Sans replied, looking about as defeated and tired as Gaster felt, "it's really a long story, and tibia honest i don't entirely understand it yet myself."

"I suppose it was something major," he eyed the young skeleton, ignoring his pathetic attempt at a joke. Alas, he considered how exhausted he appeared, even more so that usual. "You do not seem yourself."

"heh," Sans shrugged, shutting his eyes once more. He was very tired, for some inexplicable reason.

"Is it something I should be concerned about? Are any of us in danger?" he suddenly perked up, pushing down the impending worry, "Where is Papyrus?" his youngest wouldn't be able to defend himself properly, it was usually up to him or Sans to protect him from others. And if he needed it now, in Gaster's current state, then…

"nah, pap's fine," he shrugged it off, appearing as if he was going to fall asleep any moment, "i'm pretty sure we're through the worst of it. at least i hope."

"I see."

The two of them sat in mutual silence for a few minutes longer, the anxiety sitting in Gaster's fictitious stomach not knowing where to go. On one hand Sans claims there is no real danger, in fact apparently they were out the other side of it. However, Gaster cannot remember what happened, where he was, how he got here…

"i'll tell you in due time," Sans spoke again, bringing Gaster out of his thoughts, "though i guess you should rest or something."

Rest?

For what, exactly?

"Why are you withholding this information from me?" he asked instead, wanting a straight answer. It didn't make sense. None of this situation made sense.

Sans on the other hand seemed defeated, shrugging it off again and apparently dozing off. "dunno."

"Hmm." Perhaps he will get better answers when Sans wasn't so tired.

Or…perhaps someone else could give that information to him.

"Where is your brother?"

Sans froze, then turned to him with a narrowed expression. Clearly he was already onto him. "dunno," he said again. Not very helpful today.

"I take your ambiguity as a distraction from his near whereabouts," he stood up and straightened out his crumpled cloak, "Goodbye, Sans."

Sans snorted, "yeah, cya."

…

Eventually, Gaster found Papyrus in a park. Most strangely and perhaps horrifyingly of all, he was handing out food to humans. Free food. To humans. The older ones seemed sceptical, but the children, around the same age as Asriel or younger, found the entire thing extremely entertaining and probably thought Papyrus was a human in costume.

But if anything would convince Gaster that they were on the surface, this was definitely it.

He cautiously walked over, being careful not to make eye contact with any of the humans.

Though if this is the new normal, I will have to get used to being around them again soon.

"Papyrus," he called, striding over to his food stall, free food! written in crude crayon against a white banner.

The tall skeleton paused and searched around for the voice, until finally falling upon Gaster.

"Oh, hello!" Papyrus smiled, handing him a plate. "Would you like some? It's not just for humans you know!"

"Hmm," he stopped and chuckled. Never change. "I will be fine. I have some questions for you. I'd like to jog your memory about something."

"Really?" he stopped serving out plates and turned his attention towards him, "Go right ahead! My memory is excellent."

"What do you remember of the past few days?"

It was probably an odd question to sought someone out for and ask, but he had to get answers from somewhere.

Papyrus frowned, perhaps a little more so than was normal with the harsh sunlight of the surface blazing down on them.

"Well, I don't remember exactly, they were normal days after all."

"Normal?"

"Yes," Papyrus turned his head, in thought, "It's been a normal week for me. How about you?" he smiled innocently.

Gaster sighed, "That is not what I need to know. When did we get on the surface?"

Something in Papyrus' face changed, as if he twigged that Gaster was really asking something else of him.

"Last month…" Papyrus said slowly, taking a step back, "What's the matter?"

Did Papyrus not know? Did he have a lapse in memory too?

"Do you feel like you have forgotten something?"

At that, Papyrus laughed a little, "No? Are you okay?"

Gaster frowned but started to back away from the conversation, "I am fine, never mind. Forget I asked of this," he made his way forwards the exit for the park gates.

"Erm…" Papyrus loosely followed him from behind, "Maybe a little bit? It's very normal, it's nothing to worry about though!" he continued to follow him, at a near sprint now that Gaster was trying to stride further and faster. "It's like when you walk into a room and forget about what you're doing!"

"Stop following me, Papyrus," he muttered, wanting some time alone to think this through, not listening to bumbling nonsensical gibberish from behind.

"But maybe I can help!"

Clearly you cannot.

This is different to simply forgetting what you are doing. This is major.

"Please! Stop running away! I can feel it too!"

Gritting his teeth, he turned around and uncharacteristically yelled, "I am not running!"

"hey, don't yell at my bro."

Sans.

With a silent bur heavy sigh, he watched Sans magically, literally, appear from behind.

Those damn 'shortcuts'.

Sans gestured for Papyrus to back off. Perhaps he had a change of mind about telling him what's really going on here. Either that or he's about to unleash a ridiculous lecture about yelling at his brother.

"you died."

Gaster huffed. "This is no time for a joke, Sans."

"that wasn't a joke," those empty eye sockets are back, "i've already asked pap and he doesn't remember either. and I don't want you freaking out the rest of the village so yeah. you died and that's why you feel like you forgot something."

He blinked, at a loss for words for a moment. "Surely, I would remember dying?"

"there was a paradox, you were the main cause of it. everyone's memories were wiped except mine, and probably Frisk. i won't tell you how, or you'll cause another one. just don't tell anyone, especially not pap."

"Surely you cannot expect me to believe this?"

"dunno what else to tell you," Sans shrugged, and began walking the other way, "that's the truth of it. like i said earlier, cya," and strolled off.

Gaster watched him take a few more steps away, before calling after him, "Sans," he began to follow him in the same way Papyrus had done minutes earlier. Sans turned around sluggishly. "Who is Frisk?"

Apparently, that question was deserving of a snort.

"of course you forgot her too," he chuckled to himself with a hint of malice, shaking his head, "oh well. you'll find out soon enough."

Interesting. Very interesting.

He took off back home. Or, as home as he could possibly get on the surface. The entire ordeal was odd, one minute he's living in the familiar, calm atmosphere of Snowdin, then the next time he wakes he's on the surface. It's as if the house had nonchalantly teleported along with the rest of the underground and no-one thought to tell him about it.

And the memory loss? His apparent death?

The truth behind it was unknown to him, and Sans looked at him no longer as a father, but with spite. But Papyrus…Papyrus continued to treat him as family as if nothing happened. What could he had possibly done to bring Sans to look at him the way he does now?

He decided he would learn about the truth in due time, one way or another he would get the information out of Sans, perhaps win his trust back. His friendship back. Whatever it was that he had done…clearly had an impact on the whole of reality as he knew it. And Sans was the only one that remembered any of it.

What a burden to have.

He has changed so much.

What else had happened while he was supposedly gone? What was the story behind Frisk? Had she something to do with it?

Either way, it seemed he had missed a lot. It was like waking up to a new world, literally. But there were so many new factors to consider, so many gaps to fill in.

How…exciting.

Approaching the front of the house, he noted the younger human children playing with child monsters in houses beside his. Neighbours, yet another new concept to live with. And so many of them, too. They appeared to be living in harmony with one another.

This new world was extraordinary at the minimum, but he could certainly get used to this.

Satisfied, he closed the skelebros front door. Although he kept any thought that even suggested a subtle sign of emotion to himself, he couldn't help but be even the slightest bit grateful that he, of all monsters, had been given a second chance to live. Coming back after death with no-one in the world but Sans to remember it.

Who else could possibly do the same?

END