Asgore flinched.

Frisk clutched their chest.

And Sans? Sans got angry. Part of Sans, the cold, clinical part of him that that had been trained to analyze situations whispered "you know this is a different Chara. There's no reason to be angry yet." The rest of Sans, however, threw logic out the window. From his frozen, stiff stance, hands shoved in his pockets, to his locked up, humorless smile, to the dark pits of his pupil-less eyes, rage was written in every line of Sans's body.

He managed to grind out one, single, accusing word through his wide grin.

"WHAT."

The amalgamated Gaster recognized this behavior, knew how close Sans was to snapping. And, knowing exactly what Sans was capable of, he shuffled backward a bit.

"Sans. Calm down. Chara is royalty. Explain the situation to us."

Sans didn't respond. He remained frozen as the analytical side of him tried to get his emotions under control.

"Chara," Frisk said, stepping forward to speak for Sans, "is the reason we need your help, Gaster. You know the demon thing, that Sans mentioned? Well, that's what Chara turned into. They used determination to make the entire underground into their own personal game and killed everyone, over and over. Now they're loose on the surface and we need your help to stop them. They-"

"How," Sans snapped.

A pause.

"Pardon?" The goopy Gaster inquired.

"How is Chara still alive? They first fell down here centuries ago. Humans don't live that long. So how are they still kicking?"

"Ah," the amalgam Gaster answered, "The answer to that is, in a word, determination. Red souls' main power is time manipulation, so it seems logical that Chara has been able to use their ample supply to extend their lifespan. That's only a hypothesis, though. Chara has refused to allow this dimension's Gaster to examine their soul, and of course, I've never met them."

Sans hummed, stroking his chin thoughtfully as his brain connected dots at a frightening pace.

"When," he asked slowly, "did this world's Asgore die? Wait, no, let me guess; It within a few years of Chara first falling down."

The solid Gaster seemed concerned as he answered. "Yes. Why... No, how did you know that?"

A wordless snarl tore itself from Sans's throat as he punched a wall.

"I knew it!." He took a moment to compose himself. "That brat did the same thing iback home. They and Asriel made Asgore a butterscotch pie, except they "accidentally" used buttercups instead of butterscotch, and it just so happens that buttercups are poisonous. 'Course, I'm pretty sure Chara knew that. They were practicing. They just wanted to see if the poison worked. Looks like it worked a little too well over here, and it killed your Asgore."

Both Gasters remained in a stunned silence before the solid one responded.

"Sans, do you expect us to believe that Chara intentionally poisoned their own father just to test the effectiveness of a poison?"

Sans's face remained frozen in his unfeeling grin, but a sneer crept into his voice as he answered coldly.

"What you don't understand here, Gaster, is that that little brat is more of a monster than we are. They don't care about anyone besides themself. Looks like your Chara was too much of a coward to carry out their plan, or maybe just bailed when they accidentally killed Asgore, but let me give you the rundown of what would have happened if Asgore had gotten better. I told you that it was a test, right, of the effectiveness of buttercups as a poison? Well, Chara wanted to use them to poison themself, so they would die and Asriel would absorb their soul, becoming a god. Both of them had this whole plan worked out, Gaster. After attaining godhood, Asriel/Chara would pass through the barrier and kill a bunch of humans. Why? Because all Chara knows how to do is hate and kill. Probably convinced Asriel it was to get some souls to break the barrier, or something. Thankfully the little brat's plan was ruined when Asriel resisted their influence. Got both of them killed in the end, leaving their soul to rot."

"Sans, are you seriou—" the amalgam began, but Sans cut him off with the tone of someone who had just gotten a joke and realized it had been on them.

"No, no wait. It gets better. So after that little shit tore the royal family apart and threw the rest of the underground into chaos, they waited, getting more broken and more powerful all the while. Then, a long time later, Frisky here comes along. Long story short, Chara ends up possessing Frisk. Killed the entire underground, Asriel, Toriel and Asgore included. Over and over again. Dozens, hundreds of times." Sans's voice faltered and dropped to a harsh whisper. "Gaster, because of how… how you… taught me, I never forgot. At least everyone else had the mercy of forgetting each time Chara reset the timeline. But no, not me. Not Frisk. We remember. Killing, dying., time and time again with no power to stop it. Only reason we're here is because Chara let us come to the surface, and now they're looking for a stronger host. If they succeed, they will kill everything and everyone. But hey, enough about my feelings. It's not like they make a difference."

A frenzied energy had entered his voice with those last few words and he abruptly clammed up, his brain trying to find some problem, some puzzle to solve. His mind raced, analyzing everything the Gasters had said previously, looking for something, anything to distract him from the raw pain and hurt and fear and broken mess of emotions that were threatening to spill out. Finally, he found something that seemed off, and furiously picked it apart in his head.

Frisk, standing quietly by Asgore, saw Sans begin to shake and sweat, blatant panic in his eyes. From bitter experience, they knew the signs of flashbacks, of anxiety attacks, and that was exactly what they saw in Sans. They walked up to him, to the amalgam Gaster's horror, and gently placed a hand on his shoulder.

"Sans," they whispered. "Talking about it helps." Somehow, Sans managed to look clammy when he glanced down at Frisk. That shouldn't have even been possible for a skeleton, but Sans managed it anyway.

"Not me, kiddo. It's not important right now, anyway. What is important, is that I've figured out exactly why Chara won't let you examine their soul, Gaster." Sans said, shifting his attention back to the solid Gaster.

Frisk watched Sans's eyes carefully, watched him shove all that pain into a dark corner as he explained his conclusion to the Gasters.

"The reason is that if you were to do so, you would find that it's not just a human soul anymore. I'm willing to bet that they absorbed Asgore's soul after he died. That would also explain why they've lived so long. Determination can do a lot, but even it has limits. On the other hand, boss monsters live for a very long time, so absorbing one of their souls should make even the least determined human live much longer." His attention shifted to the amalgam. "Come on, Gaster. Of all people, you know that determination alone isn't enough to make Chara live this long. Solid Gaster, you should check up on that. The rest of you, come on. We're going home."

Sans was met with a stunned silence as his audience tried to process his sudden 180 in the flow of the conversation.

"Wait," Asgore rumbled hesitantly, "You want to go back home now? We just found out that Chara rules this underground. One tiny push could send them and the rest of the underground into chaos, and you want to just leave? Sans… we can't do that."

"IT'S NOT," Sans said, rounding on Asgore. "OUR. PROBLEM." His pupils had contracted to mere pinpricks. "Frisk doesn't have control of the timeline back home, let alone here, so if we die, we are finished and everyone back home is screwed. I'm not risking our universe just so we can see if this one needs fixing."

"Sans," Frisk said quietly, tugging his sleeve. "I get where you're coming from, but if their Chara is anything like ours, then we can't just sit by and do nothing. It's not our problem, no, but innocent monsters could get hurt, Sans."

"I agree," said Asgore. "The strong are obligated to help those in need, so let us go and confront this Chara. If we cannot handle this Chara, then what makes you think we can handle our own? We have nothing to lose, Sans."

Sans still seemed unconvinced.

"Sans," the amalgam Gaster said softly, "I have lived in this world for so long. Please do not let it crumble."

Sans stared at his friends with a pained expression. He trusted all of them, especially Frisk, but they were all asking him to do something that the analytical part of his mind screamed was a bad idea. "Why?" he thought, "Why won't they listen?" But he knew that look on Frisk's face, that squinty-eyed expression of determination. They were going to keep pestering Sans about this, and try it by themself if they had to. Mentally, Sans heaved a sigh of defeat, then steeled himself, putting his training as a tactician to use.

"Fine," he snapped. "We'll stop Chara." Of course, by 'stop,' Sans meant 'kill,' but he wasn't about to let anyone know that. Despite all that Chara had put Frisk through, they still might try for mercy. But Sans knew better. Something that had been drilled into his head since the day he started learning to fight was that if you attacked anything, it had to be with lethal intent. Anything less would get you killed. Sans held no mercy for any opponent, especially not that demon, Chara. "But," he continued, "while I think we've got plenty to go on here, but I want to make sure the ball is squarely in our court before we do anything. I'm sick of that brat having the upper hand. So Gaster, tell me, how many humans are in the underground, and what are they capable of? I ran into one, I think they call him Integrity or somethin', but he could use magic. That's not normal where we come from. Is this magic unique, or is there anything we have to look out for?"

The solid Gaster adjusted his glasses, shifting gears to professor-mode.

"Besides Chara, there are two humans in the Underground, referred to as Integrity and Patience, with blue and orange magic, respectively. Their magic is different from monster magic in that while monsters summon projectiles, such as my tesseracts," —Gaster briefly summoned one as an example— "human magic involves manipulating their environment or their opponents. Integrity has gravity-based blue magic, where he can move objects by altering their gravitational fields, whereas Bravery has orange aspect fire magic."

While Asgore and Frisk were engrossed in the explanation, Sans had locked eyes with the amalgam Gaster, an angry grin growing by the second. They abruptly cut off the staring contest when the solid Gaster finished his briefing.

"I don't know if Chara can use magic, but just because nobody has ever seen it does not mean that they can't."

"Well that's just great," Sans grumbled. "We have to jump into this without knowing whether Chara can even use magic. That's a pretty big variable, dontcha think?"

"Sans, I feel your version of Chara is far less reserved than ours." Said the solid Gaster. "They spend most of their time alone and they don't talk very much, to anyone, not even Toriel."

Only Sans noticed Asgore stiffen at the name.

"They are very secretive. There is no practical way I can think of that we can ascertain their magical abilities other than a direct confrontation."

Sans sighed in irritation. "You're right. Even if they can use magic, I doubt they would use it in anything besides direct combat if they're as cautious as you say. Becoming a demon made our Chara incredibly powerful, but since yours is still alive they shouldn't be quite so strong. Then again, they have absorbed a boss monster soul, assuming I'm right about that, which would certainly make them dangerous. Still, I'm not going into this without some sort of insurance. Gaster, you mentioned that when our Gaster appeared he sucked up some determination? Do you still have any?"

"Yes…" the solid Gaster answered, not sure exactly where Sans was going.

"Can you get some? We're going to need it," Sans said as he turned on his heel and disappeared into one of the lab's rooms. Gaster went through a different doorway. The sounds of clinking glass and shuffling paper emanated from both doorways. Gaster came back first, holding a mid-sized red canister with some sort of hazard label plastered to its exterior. Sans emerged soon after with an armful of medical supplies and unceremoniously dumped it on a table.

"What I'd like to do, if you're up for it, Frisk, is temporarily hijack this timeline from Chara. When Chara possessed you back then, they supplied your determination. That's why you lost control over the timeline when you forced them out, but I've got a canister of distilled determination here. What I want to do is hook you up to an IV and put some determination in ya. You're human, so you should handle it just fine, and it should jack up your determination levels to the point where you can fight Chara for control of the timeline, or even completely take it over. The second we came over here, we were placed into Chara's game. If we spook them to the point where they try to reset or LOAD a different save… well, I'm not sure exactly what would happen, so let's avoid it."

"If I may interject," the amalgam Gaster said, raising a finger, "I'm fairly sure I can guess what would happen. At best, what happened to me will happen to you. At worst, you'll be erased from existence. See, when the core sort of blew up in my face, I didn't just pop over here immediately. For a time, I was stuck in a place beyond time."

Frisk's squinting intensified.

"What?" They said flatly.

"It was a space between universes," Gaster continued. "I eventually came to refer to it as the Void. It was dark. That's not anywhere near descriptive enough, but words fail me. Dark, darker yet darker…" Gaster's pupils disappeared and he began to shiver. It wasn't the way Sans did it, the abrupt, threatening disappearance of those small lights, rather they slowly faded, the light in Gaster's eyes dying as he remembered… "Time did not seem to pass there. I floated for what felt like years, trying to find something, anything that I could sense. No sight, not sound, no touch, just emptiness. For a time I could not tell if I existed. But finally, I started to see scattered bits of movement, strings of numbers; code."

The plates that constituted Gaster's face started to slide apart, their owner so lost in memory that he couldn't even properly maintain his physical form.

"I tried to grasp the fleeting strings of code that were within my reach. My fingers past through it, but for a fleeting moment a bolt of understanding shot through me. It was a set of instructions of some kind. Gradually I could see more and more of this code, fleeting in the the dark. When I would touch it, I could feel what it was for. And this code, Sans, was for building worlds. Gravity, friction, momentum: it was all there. And it didn't stop at physics, oh no. I found the code for everything. For you, for Asgore, all the buildings and residents of Snowdin, all in letters and numbers. I saw all of us at the most basic fabric of reality." The light slowly began to return, his form regaining its structure. "The reason I am they way I am," Gaster demonstrated by raising a dripping arm, "Is not that the core explosion damaged me. The code controls everything, Sans. When I finally emerged from the void into this universe, the code saw that I did not belong. This world has one Gaster, not two. So I was reduced to a lesser state of being. Only by infusing myself with determination was I able to regain physical form, and a limited one at that."

"That's… thought provoking," Sans said, "but where does erasing us from existence come into play?"

"Tsk. Impatient. I was getting to that," Gaster chided. "Normally, what happened to me would have happened to you, but all of you can be here because there are no direct copies of yourselves in this universe. Their Asgore is dead. They do not have a Frisk. And Sans, you… you don't exist either. None of you is a duplicate of any code. But if Chara LOADS to a point after you came here, the code will notice that you three are out of place and try to erase you, reducing you to something like me. If Chara LOADS to a point before you arrived, you will cease to exist. Determination is powerful, but it cannot act across universes. It will not take you home, rather you will simply be erased and forgotten."

The room remained silent for a solid ten seconds before Sans, concerningly unshaken, said in a businesslike manner, "Well thanks for settling that, doc. We don't have a choice in the matter, then. Frisk, you need to take the reigns from Chara. Like I said, you'll be fine. So are you up for it?"

Frisk remained silent for a moment, contemplating the choice. They trusted Sans, believed that the distilled determination would do them no harm, yet they still hesitated. They knew there was no rational reason to refuse, but that primitive, fearful part of their brain screamed loudly enough to hold logic at bay. That extra determination would throw them right back into the game, the living hell that Chara had forced them to endure for years, where lives were just pieces on a board to be manipulated, used. They shuddered. "But this isn't just about me," they thought. "This world needs us." They slowly drew themself up, hardening both their gaze and their resolve.

"Let's do it."

It didn't take long for Sans to get Frisk ready to go. He put some distilled determination into an IV bag and stuck a needle in the crook of Frisk's elbow. The original plan was to follow standard procedure and suspend the bag from a pole, but Frisk refused to stay behind. Sans had wanted to leave them in the lab since they would be the only thing preventing Chara from playing with the timeline and, by extension, destroying all of them, but Frisk refused to stay behind, so Sans had to improvise. He ended up strapping the bag to Frisk's back, under their shirt, where Chara hopefully wouldn't notice it.

"With the size of the needle and the amount of determination in that bag," Sans said, "You should be jacked up enough to take over the timeline for an hour or two. It if isn't over by then… it won't matter, anyway." Sans looked over at the solid Gaster. "Are you sure there's no way to gather intel on Chara's abilities?"

Gaster sighed. "Yes, Sans. I have worked with them for decades trying to answer that question and have learned nothing. I cannot force them to reveal their secrets"

Sans sighed in irritation, then looked to Asgore. "Fine. With that in mind, we want to end it as soon as possible. We don't know enough. We don't know what Chara is capable of, we don't know if they will be alone. Asgore, you may need to help me, and that might mean fighting Chara. Can you do that?" Sans's tone was deadly serious, in spite of his ever-present grin.

Asgore's eyes wandered as he thought. Despite his massive power, he had never really liked fighting, and now his best warrior was asking him to fight his own child.

"No," he said, thinking aloud. "They're not Chara. Not anymore."

He slowly met Sans's gaze.

"I will fight with all my strength to put Chara to rest."

Sans nodded grimly.

"Good."

Then Sans did something nobody had ever seen him do before.

Hands still firmly in his pockets, Sans teleported everyone in the room without establishing physical contact, reality twisting and contorting for a split second before spitting them back out in the throne room.

There were three persons of interest. On one side of the throne stood the human Sans had encountered. On the other, was a lanky, pale human with short brown hair. Both had their attention focused on the person sitting in the throne.

A little bit older.

A little bit bigger.

But.

Unmistakably.

Chara.

A/N: Heyo! Got another one out, and this time a bit quicker, eh? Thanks so much for reading, and as always, R&R!