True Infinity

Infinite growled at the threat, while the skeleton just grinned. "Right, I never introduced myself, did I? Name's Killer, Tall, Dark, and Handsome. Or at least, I assume so under that mask of yours."

Infinite was annoyed at the pitiful attempt at flirting. "What makes you think I care about who you are? And why would I ever listen to you?"

Killer's smile twitched slightly before continuing. "'Cause you ain't got much choice. The Boss may have told me not to hurt ya, but that doesn't mean I can't rough ya up a bit. 'Sides, it's not like you can beat me, and you know that don't ya?"

Infinite was upset by the statement, but it was true. The energy levels of Killer were several times higher than Sans, whom Infinite was confident he could challenge, but not completely convinced he could beat. Against someone multiple times stronger than that, it was already a foregone conclusion.

Killer grinned at Infinite's clear inner conflict before swiping Infinite's blade right out of his hands and pinning the jackal to the ground. "Well, would you look at that? Guess I win. Didn't expect ya to let your guard down like that. Were you CHECK-ing me out?"

Infinite gritted his teeth as Killer mocked him. How upsetting, to think he would be humiliated again like this.

"Killer, that's enough. If you antagonize him any further, there's no way he'll even hear what The Boss has to say." Another skeleton appeared, this one wearing a red scarf and a hoodie that somehow covered most of his face.

Killer huffed before getting off Infinite. "Honestly, you're no fun, Dusty."

"Don't call me that. It's Dust." Dust glared at Killer.

Dust approached Infinite while Killer stood back. "I'm here because, one, I don't trust that idiot not to screw this up, and two, because The Boss wants to come to a sort of agreement with you. Now, I don't know what exactly he wants, but the fact that he's even bothering to consider your opinion at all shows how much The Boss wants this."

Infinite narrowed his singular visible eye. "And why exactly should I care about what your leader wants?"

Dust huffed before responding. "Because The Boss knows how to get you back to your Multiverse, True Anomaly. If you give The Boss what he wants, he'll give you what you want."

Infinite was shocked by the revelation but didn't show it. "I see, so this boss of yours claims to know how to return me home, then? Fine, I might as well see what he has to say. Anything to get me out of this annoyingly peaceful universe."

Killer grinned while Dust gestured to a pitch-black portal that appeared near them. Infinite tensed as he passed through the portal after the other two.

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As soon as Infinite exited the portal, he noticed how clean and tidy everything was. He seemed to be in some sort of high-class mansion or perhaps a castle. Whatever this place was, it gave Infinite a strange feeling of dread. He could feel the darkness surrounding it; it was quite intense.

Killer grinned at Infinite's discomfort. "Welcome to The Nightmare Palace (name pending). Well, how do ya like it?"

Before Infinite could respond, however, a very large skeleton that towered over him appeared suddenly. Part of his skull was missing, with only a single crimson eye staring at him. "You're... back. How... did... it... go?"

Infinite was confused by the delayed speech. It seemed this one had trouble speaking for some reason. Killer grinned, raising both his arms behind his head. "Well he's here ain't he, Horror?"

Horror simply nodded while Dust continued down the hallway. "Stop wasting time, Killer. The Boss isn't someone who should be kept waiting."

Infinite appreciated Dust's curtness and seriousness. He was certainly far better than Killer, who reminded him far too much of that blue hedgehog. "Yes, Dust is correct. I'd rather get this over with as fast as possible."

Killer pouted, while Dust nodded at Infinite, and they continued down the hallway with Horror accompanying them. Infinite felt uncomfortable, both with the number of people around him and with how powerful he sensed them to be.

Infinite noticed several others at the corners of his vision while moving toward the source of the darkness. One had a cracked skull with bloody teeth and seemed to be muttering to himself while carrying a skull.

There were also three skeletons in a nearby living room who were talking to each other. One looked almost identical to Sans except for the seven skeletal hands floating behind him which had strange holes with red dots in the middle, that and the large gash in his torso. The other seemed like a skeleton but made entirely out of pitch-black flames with two red eyes. The last wore a hoodie and scarf similar to Dust but the coloration was mostly red and black instead of blue and purple.

Both Dust and Horror couldn't help but tense a little around them as Killer's smile became noticeably more strained. They said nothing as they moved past them but Infinite could tell they weren't welcome here. Horror gently pushed Infinite who had begun to lag behind as the skeleton made of black flames seemed to strangely call to him.

The jackal glared at the near-giant who responded. "The....Lord's....servants. Best....not...to...stay. Not...welcome. Dangerous."

Infinite just huffed at this in annoyance. He didn't know who this Lord is but apparently they weren't well liked. He was pretty sure they weren't this Boss the other's were referring to either. Regardless it didn't matter right, besides he had other things to do.

Another was covered in black and white straps with a long scarf, carrying an oversized butcher knife on his back. His eye-lights were x-shaped, one red and the other purple. He had significantly more energy than any of the others, save the dark presence that undoubtedly belonged to this Boss.

Killer grinned at the skeleton. "Well heya there, Crossy. You're looking as serious as ever. I thought The Boss sent you on a mission to Outerswap?"

Cross ignored Killer and continued to stare at Infinite, which irritated the jackal. "Is there something you want, or are you just going to stare?"

Cross scoffed before responding. "I don't know what The Boss sees in you. As far as I can tell, you're hardly anything special, and even if you were, he shouldn't bother with debasing himself to accommodate you."

Infinite's eyes narrowed at Cross, who walked down one of the hallways while Killer whistled in amusement. "Well, he's as unfun as ever. Got a real stick up his non-existent ass, he does. Well, no time like the present; let's go see The Boss."

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Dust sighed as they finally arrived at a large, ornate black door covered in various turquoise embroidery centered around a glowing purple crescent moon. Infinite was mildly impressed by the design; this boss had very good taste. As they approached, the doors opened on their own, revealing the large room beyond them.

The expansive room was lavishly decorated, the kind you'd expect to see in grand palaces. The walls were adorned with banners that bore similar iconography to the main doors, while several smaller doors dotted the area. A large pitch-black throne, with a purple carpet leading up to it, stood in the center of the room. Behind it was a massive stained glass window that depicted a large tree with black and gold apples dangling from its branches, illuminated by light from a purple moon.

Killer looked around, confused. "Huh, weird. Thought The Boss would be here. This is usually where he is when we have a new member. Must be in the study then. Well, guess we're heading there. C'mon, guys."

They walked through one of the larger doors, leading to another room filled to the brim with various books. There were multiple floors of books of all kinds, stacked so high that Infinite almost couldn't see the ceiling.

Before Infinite could say anything however, he felt a sudden wave of intense dread. As he looked toward the end of the room, where a large table surrounded by couches and chairs sat, he spotted a strange being near a crackling fireplace.

It was a very tall skeleton, covered in black goop with a turquoise tint, and various tentacles wriggled from its back. Only one of its eyes was visible, while the other was covered by the same goop. The visible eye was currently focused on the book in the skeleton's hand.

Infinite gulped as the singular slitted turquoise eye turned toward him, his instincts screaming that he was in danger. "Ah, so you've finally arrived, have you? Good, we may begin then. Good work, Killer. You'll find your reward in the second repository on the third floor."

Infinite shivered slightly at the dark, deep tone of the skeleton's voice. It felt as though it was trying to penetrate his mind and soul, making him even more wary of the being in front of him.

Killer grinned before walking off, while Dust and Horror chose to stay on the outside of the room. The being smirked slightly at Infinite's discomfort. "You don't need to be nervous, you know? If I wanted to hurt you, I would have done so already, Infinite."

Infinite paled slightly upon hearing that, realizing that the thought of the skeleton penetrating his mind and soul had been more literal than he had believed. The dark skeleton continued, savoring the jackal's growing negativity. "Anyway, I had you brought here after observing that little spat you were caught in the middle of in the universe where you showed up. It was certainly amusing. I never expected those two to go that far in a main AT of the Original AU."

Infinite clenched his hands in frustration at the revelation. So he had been watching this whole time, and Infinite had never known. "If you were observing the entire time and knew I was in no shape to fight back, why bother making it seem like your invitation was a request?"

"Because, unlike my foolish subordinates, I know exactly what that gem of yours is capable of. I wasn't sure of its exact capabilities at first, but now that we're face-to-face, I've been able to confirm its power with my own eyes." the being stated concisely.

"And I must say, what an incredible power it is. But that's neither here nor there for now. How about introductions? I am Nightmare, God of Darkness, Embodiment of All Negativity in The Multiverse, and the ruler of this palace. A pleasure to make your acquaintance." Nightmare introduced himself with a slight flourish.

Infinite simply nodded without saying anything, not trusting himself to speak for fear of showing any weakness in front of the deity. Nightmare chuckled at Infinite's poor attempt to appear strong. "Well, now that introductions are out of the way, we can move on to more important matters. I'm sure you already know this, but this Multiverse operates under very different rules compared to yours. If you want to survive here, you must understand both its rules and its hierarchy."

Nightmare continued as Infinite listened. "I took the liberty of performing a CHECK on you. Given your lack of reaction, you are either unable to sense it or don't realize its importance. I will remedy that. Though I must admit, I didn't gather as much information as I expected. Here, take a look."

Nightmare waved his hand toward Infinite, revealing a floating panel of information.

Infinite

LV-12

HP - ERROR

ATK - ERROR

DEF - ERROR

Infinite was confused as he looked at the information. It resembled stats you would see in a video game.

"This is known as a CHECK, which, through a soul scan, reveals information about the target in a system format. The more powerful the scan, the more useful the information. You're the first person I've met where I couldn't gather much information." Nightmare remarked.

Infinite was both surprised and upset by that revelation—so that's what that had been? It had been so subtle and weak he hadn't even thought to protect himself from it.

"As for what ATs and AUs are, an AT stands for Alternate Timeline, while an AU is an Alternate Universe. The universe you ended up in was the Main Timeline of the True Pacifist Route of Undertale, also known as the Original Universe. As the name implies, Undertale was the very first universe to exist, and all other ATs and AUs are based on it. If any damage were to come to it or its timelines, it would reverberate throughout the rest of the Multiverse, causing significant problems for many." Nightmare explained.

"So that's what those three were talking about and why they were holding back so much," Infinite concluded.

"You catch on quickly. Good, that'll make things easier. As for the hierarchy, The King, the Oldest and Greatest of the Gods, stands at the top. He is the Supreme Ruler of the Multiverse, but he rarely ever gets involved and frankly couldn't care less about what happens, as long as there is balance. After him are The Lord and The Abomination, though I know little about them due to their isolation. Though The Lord did send an envoy not too long ago. Then there are The Creator and The Destroyer—Ink and Error, whom you've already met. Ink is the God of Creation and the Protector of Universes, I'm sure you're familiar with his...unique personality. Error is the God of Destruction and the Destroyer of Universes. He believes anything not part of the Original Universe is an abomination that deserves to be destroyed."

Nightmare paused for a moment before continuing. "Finally, there are the other gods. Myself, Dream, Reaper, and others fall into this category. Dream is my polar opposite in every way, and unfortunately, he is also my brother. And yes, Reaper is exactly who you think he is. Any questions?" Nightmare finished.

Infinite held his hand to his mask, processing the flood of information. "I see. That is a lot to take in. But if you're some kind of god, why do you need me?"

"I don't need you. I need the Phantom Ruby. From my observations, I've concluded that not only is the gem fused to whatever approximation of a body you have, but it's also slowly merging with your soul. While I could remove it, doing so would be difficult without damaging it." Nightmare responded.

Infinite sighed at this but wasn't particularly surprised. "Then why do you need the ruby? From what I can tell, you're far more powerful than even Super Sonic. I doubt the Phantom Ruby would do much to improve your abilities."

Nightmare was amused by Infinite's remark but didn't show it. "It may seem that way at first, but your gem has the power to defy rules and limits—even on cosmic scales. For someone in my position, that's very useful, especially since there are powers it possesses that even you are unaware of."

Infinite huffed. So the god was claiming to know more about the ruby than he did? "Fine, I can believe that. But why bother 'inviting' me here? Why not just force the issue?"

"The reason is simple: your gem reacts to emotions and thoughts. If I were to try anything unsavory, it would likely respond to your distress, potentially unleashing its full power. Its reality-warping properties would cause significant damage to me—perhaps even permanently—but you would certainly not survive such an event." Nightmare explained.

Infinite was surprised by the admission. He had always known the original ruby had powers that surpassed even the Chaos Emeralds, but he didn't realize the extent of it. To harm a god so thoroughly something even a Super form couldn't really do, at least not on its own. Perhaps he could-?

Nightmare clasped his hands on the table and leaned forward. "Now, all that remains is my offer. You will use the Phantom Ruby's power to help me achieve my Full Power, and in return, I will help you understand its abilities and provide you with a way home once you've upheld your end of the deal. So, what do you say, Infinite? Will you work under me, or not?"

Infinite thought about it for a moment, but he had one last question. "How do I know you won't just go back on your end of the deal?"

Nightmare smirked. At least he wasn't dealing with a fool. "If you're truly that concerned, we can make a soul contract. Of course, if we do, it will bind you just as much as it binds me."

Infinite considered this before nodding. Nightmare grinned and raised his hand toward Infinite, who reciprocated the gesture. As they clasped hands, a black apple appeared in front of Nightmare's chest, while a dark magenta, upside-down heart with black stripes appeared in front of Infinite.

A prismatic thread wrapped around their arms before binding their respective souls. Infinite suddenly felt a strange heaviness within him, the weight of the soul-binding contract he had just agreed to.

"There, the contract is sealed. Welcome to my palace, Infinite." Nightmare stated ominously.

Infinite nodded at his new... boss? He didn't like the idea of following someone else, but this was his best chance at getting what he wanted. Besides, the contract should at least make betrayal unlikely. He wasn't naïve enough to believe everything the god said, after all. Though he knew he would have to figure out a way to break the contract once he got what he need out of this place. The last thing he wanted or needed was something binding him to someone else once he had the power he desired.

"Now then, time to start your training. Dust, get in here." Nightmare called.

"Yeah, boss?" Dust replied as he entered the room.

Nightmare pointed toward Infinite. "You are to train Infinite to improve his mastery over the Phantom Ruby. Use whatever means you deem fit, but ensure he is not permanently harmed. Is that clear?" Nightmare said as the room darkened slightly at the last statement.

Infinite shuddered slightly at the sudden feeling of dread, while Dust nodded. "Got it, boss. I'll make sure he's up to standard before his first mission. Come on, Infinite, let's go."

Infinite was slightly annoyed but followed. He wasn't sure how powerful Dust was, but he knew Dust was significantly stronger than he was at the moment. Maybe he might actually learn something, at least in regards to his more esoteric abilities. There's no way anyone here could teach him anything about swordsmanship, he was the best at that after all. Even a different multiverse wouldn't change that.

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They exited the throne room and descended a large staircase. Soon, they arrived at a wide, spacious area filled with various targets and dummies.

Dust turned around and faced Infinite, raising his hand. Before Infinite could react, he was enveloped in a purple glow and hurled violently into the wall. "First lesson: never let your guard down."

Infinite coughed from the impact, more shocked than hurt. But before he could respond, he was thrown into another wall. And another. This repeated several times, much to Infinite's rising anger.

With a growl, Infinite conjured a red cube that released a large beam toward Dust, who effortlessly blocked it with a small wall of purple bones. Infinite quickly formed a larger cube, sending a volley of energy blades at Dust. But Dust vanished just as the blades tore through the bone shield.

Sensing an attack from behind, Infinite created a curved blade and swung, but it was too late. Dust's telekinetic grip slammed him into the ground. The skeleton stood behind him, hand raised. Dust slightly lowered his hand, causing the ground beneath Infinite to crack from the increased pressure. Infinite groaned as his body creaked under the weight.

Dust watched him apathetically, but before he could speak, Infinite unleashed a burst of red energy that knocked him back. Dust skidded several dozen feet across the ground, while Infinite, now panting, struggled to maintain his composure. He was frustrated by how exhausting even a small display of power had become, but he wasn't about to give up.

Infinite raised his blade as he dashed towards Dust, cracking the ground as he moved so fast as to create over a dozen sonic booms in less than a second. The jackal rapidly swung and pierced his sword towards the skeleton who quickly teleported away only for Infinite to immediately predict his new position and create dozens of air slashes which flew at him.

Dust was shocked at the display, that wasn't even magic just skill and physical power. He retaliated by making multiple small pillars of flame erupt from the ground which Infinite dodged with incredible skill as he backflipped before twirling mid-air and unleashing a massive wave of pure force at Dust. He quickly appeared behind Dust who had countered the wave with a bolt of lightning and swung his blade. Dust immediately ducked before spinning around and kicking off the ground as Infinite began a flurry of strikes.

Dust was beyond surprised now, Infinite's skill with a blade was insane. Better than anyone he had ever seen besides maybe Dream and even then he wasn't sure. It was almost like some sort of macabre dance of death, beautiful and deadly at the same time. Dust was forced to put more and more effort into the fight as he struggled a bit to keep up. He had been forced to teleport multiple times already from blows he couldn't block or counter.

Both the jackal and the skeleton were growing increasingly frustrated with the fight, Infinite for not being able to get a single hit in despite his best efforts and Dust for not being able to do anything but focus on dodging due to the relentless assault which gave little time for anything else. Dust decided he had had enough of this farce and using a combination of gravity manipulation and cyan soul magic to instantly force Infinite into the ground with immense pressure.

Infinite gritted his teeth as the sudden increase in gravity strained his muscles and bones. The jackal strained his neck as he glared up at Dust while using up the last of his energy to will a massive red spear that crackled intensely with energy but before he could throw it, Dust raised his hand "That's enough, Infinite. I've seen what I need to."

"What? I don't need your pity!" Infinite growled, his fur bristling with anger. Being defeated so soundly even despite his weakened state bothered him immensely, he could tell that Dust had held back significantly after all.

"It's not pity," Dust said flatly. "I was gauging your current level. You're somewhere between Undyne and a standard Sans in terms of power, though your instincts are better than your average Sans. Your skill on the other hand for most things is about the same as a Sans but your swordsmanship is something else. Better than pretty much anyone or anything I've ever seen honestly. Not half bad, but not amazingly great either."

Dust paused, eyeing him. "You should take a shower and rest while you can. You won't be getting much of either after today. Showers are on the second floor. The boss should've already assigned you a room on the fourth."

With that, Dust teleported away, leaving Infinite to process everything. Sighing, Infinite headed toward the second floor as he clenched his fist. If his body hadn't been weakened by nearly being killed or his power's from the Phantom Ruby merging with him instead of a mere copy he could have defeated him. He hated being so weak, but that was exactly why he had agreed to this ridiculous arrangement in the first place. Besides he knew he couldn't just say no; there's no way they would have just let him go after all. What a pain.

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After a few minutes, he found the showers. Once inside, he removed his gloves and boots, checking the room to ensure he was alone. Only then did he remove his mask.

The warm water cascaded over him, soothing the soreness in his muscles. As he stood there, he couldn't help but feel irritated by his current weakness. But at least here, he had a chance to improve.

"Wow~, so that's what you look like under that mask, huh? Damn, you're even more handsome than I thought."

Infinite froze at the voice, turning sharply to find Killer leaning casually against the entrance, smirking.

Infinite immediately reached for his mask, but before he could grab it, Killer pinned him against the wall.

"Man, you're quite the looker—heterochromatic eyes, scarred face, that fur pattern. Honestly, why hide behind that silly mask? What've you got to hide, Infinite~?" Killer murmured, raising Infinite's chin with one hand.

Infinite snarled and lashed out with his claws. "Stay the hell away from me, you creep!"

Killer chuckled as he teleported out of reach. "Man~ no need to be a buzzkill. I was just making an observation."

Scowling, Infinite inwardly admitted Killer wasn't wrong. What was he even hiding from? This wasn't his universe—or even his multiverse. No one here knew him, not really.

Killer's gaze trailed over Infinite's muscular body, taking in the faded scars. 'Interesting... he's been through quite a few battles—stab wounds, gunshots, and if I'm right, some laser burns too. How fun~.' the skeleton thought.

"If you're done gawking, can you leave me alone, or do you have a reason for being here?" Infinite snapped, drying off and getting dressed.

"What? Can't I just be here because I want to spend some time with you?" Killer teased, though his grin softened into something more calculated as he stepped closer while wrapping an arm around Infinite before whispering into his ear. "A word of advice: don't act so abrasive all the time around here. It's a good way to get hurt—or worse. And watch out for Insanity. Even the boss has trouble keeping him in check."

Infinite shoved Killer off as Dust entered the room. "Ah~, don't you appreciate my company? Such a shame."

"Leave him alone, Killer," Dust said, clearly annoyed. "We have work to do."

Killer shrugged, smirking. "Oh right, you're supposed to be in charge of training him. Why don't I tag along? I promise I'll be on my best behavior."

Dust sighed. "You'll tag along whether I say yes or no. Fine, but if you interfere, I'm kicking you out. Got it?"

Killer raised a hand in a mock salute, his glowing tongue sticking out. Dust simply shook his head as he led the way out. "Come on, Infinite. Let's continue your training."

Infinite followed, Killer trailing along as they descended back to the underground training area. They arrived at a smaller section equipped with chairs and a chalkboard. Dust took the seat closest to the board, while Infinite and Killer sat across from him, awaiting the next phase of training.