Undertale - A Change of Heart



The Traveler
Sep 25, 2010
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Hi everybody! This isn't going to be 100% the same as the actual game Undertale. I have an original character in this that'll be the new "Frisk", sort of. There may or may not be spoilers to the actual game. So be forewarned, because you're reading this at your own risk of spoilers. Last but not least, Undertale belongs to Toby Fox. So uh, please read and enjoy, while I go hide in a corner. Oh and a small nod towards Camilla Cuveas on Youtube, who I borrowed a cool line & idea from.


Wake up, dammit, wake up!

It was happening again.

Where rational sense left her mind as doubts plagued her from the darkest corners of her heart. What determination she had hold of was weakening beneath the crumbling sense of her inferiority to those around her. Including those who loved her. They loved her without judgement and continued to believe in her, when she felt unworthy of it and embarrassed by her own weaknesses. She couldn't understand it at all. How could someone love her when she continued to fail? She felt like a disappointment to Sans the most, because he knew what was really going on. Even worse, she wasn't strong enough to hold her own ground against her own shadow, which loomed over her with red eerie eyes and a psychotic smile. A knife glinted in its right hand. A carbon copy of her except for the eyes.

There were only a few options left for her to choose from: FIGHT, ACT, MERCY, and RESET.

"Killed or be killed, Jeri." Her carbon copy laughed, raising the knife and threatening her with the pointy end of it.

And yet, Jeri couldn't help from asking herself, how did it come to this? Why was her carbon copy making her choose, when she was already exhausted by the amount of self loathing and pity she felt for herself? The choices she made came to her mind as she got back up and onto her feet. The light filtered in through the windows, shining down on them and basking them in a warm glow, as they stood facing apart from each other on the tile floor. Determination filling their hearts and motivating them to do this. Motivating Jeri to put an end to it once and for all.

Jeri held out her hand and called for "help".

"How cute..."

The carbon copy smirked, enjoying the way Jeri faltered when the six souls didn't answer her call. Something was wrong. Horribly wrong. Jeri tried again, focusing on her determination to set things right after all this time with a clasp of her hands, except her carbon copy teleported away from her sight before she could call for help a second time.

"You think you can win... you're wrong."

Jeri twisted around, barely dodging out of the way of a silver glint coming into view. Again, her carbon copy swung the knife at her with reckless abandon, making Jeri stumble backwards and tumble onto the floor, rolling out of way as a sharp knife struck into the floor where her head had once been seconds prior.

How did her carbon copy get so strong? Jeri wanted so badly to reset to escape this nightmare and beg forgiveness from Sans, including those she lied to, but she knew it would only be a matter of time before her carbon copy found her and killed her and everyone else for good.

"Every time you 'reset' I extracted your determination... making me grow stronger, strong enough to exist in this pathetic timeline. After all, all it takes is some determination. And what fun it's been, killing all of those monsters in Alphys lab."

"And if you had killed Sans, we could've ended this sooner and ERASED this timeline for good... But you were too weak and had to RESET. All of that determination left over from the previous resets had almost gone to waste until I found it and could take it for myself..." The carbon copy's smile grew wider, tilting her head in a playful manner as she stepped closer to Jeri.

Jeri gulped and looked up in time to see the carbon copy's knife had taken on a black glow.

"Do you know what black means?" Her carbon copy teased, slashing the empty air three times and leaving black slices of magic behind. "It means hate..."

"And now, I'll take what's left of your determination... using all of this hate from having to watch you spare everyone else's lives over and over again."

In an instant, the black slices of magic moved before Jeri could react. Jeri held up her arms over her face with her face turned away and braced for the impact except nothing happened. The familiar sound of teleportation echoed into her ears and a dizzy sensation overcame her as she gathered her bearings and found a familiar skeleton standing before her in a blue jacket.

"Human... Don't you know it's rude to start this without me? It makes me feel bonely."

A scold appeared on the carbon copy's face, ​"How predictable..."

"I'd say it's knife to see you," Sans mocked, eye sockets instantly turning black. "But I feel bone tired, and I want you to cut it out with these games already."

"You're in my way, Sans. You could join me... It'd be a skele-TON of fun if you did."

Now it was Sans turn to get angry. Nobody uses his puns and gets away with it. "Never, you Megalomaniac. Not after what you did to everyone else. Burn in hell." Upon hearing this, the carbon copy burst into an insane fits of laughter as she teleported out of the way from a set of blasters firing at her all at once.

"Sans!" Jeri exclaimed softly in shock. The last time they spoken she thought he didn't want to ever see her again.

"Heya Kid..." Sans smiled, his left eye socket closing as his right one burst into a blue flame. "Looks like you could use some help." Four blasters appeared and opened their mouths, shooting a pattern of white hot beams at the carbon copy; each one was dodged until Sans swept his bony hand to the side, turning the carbon copy's heart blue before thrusting his hand downward to smash the carbon copy into a pile of bones waiting for her.

The carbon copy having anticipated this, swept her knife into a horizontal line with a flare of red magic that collided into the bones sticking out of the floor, shattering them into pieces, and leaving her unharmed as her body hit the tile floor. Instantly she vanished and reappeared next to Sans, slashing her knife wildly around at him with slices of red magic zooming after their intended target.

Sans eyes narrowed, frustration covering his features as the carbon copy kept rushing forward to attack, striking the air with her knife as he moved out of the way each time, trying to avoid being hit by the knife or her magic with Jeri standing there defenselessly on the sidelines. Normally this would be a piece of cake only he was starting to tire out because, this wasn't the first time they've fought against each other. Those dang resets were becoming a problem and he really didn't want to pull out all the stops unless he absolutely had to. In a desperate attempt to end this fight early, he snapped his bony fingers together and a set of bones shot through the air, each one zooming past the carbon copy as she ducked out of the way. "Ha!" Sans quickly made a fist and watched in satisfaction as the carbon copy was struck down three times in the back with the bones sticking out of its chest with blood splattering onto the tile floor.

The carbon copy instantly turned to dust with its heart left in its place; its heart lost its vibrant red color until it was visibly gray and broken in half.

But it refused.

The carbon copy's heart filled with 'determination' and came together again, shining into a flash of brilliant white light.

Jeri moved to stand next to Sans, reaching out for his jacket with a hesitant hand only to see Sans eyes fall upon her. His smile was one she knew well. It wasn't his real smile but his, 'you're going to have a bad time' smile, which showed his canine teeth.


"Kiddo, what kind of game are you playing at?

It felt like a bucket of cold water had been dumped over her head as her eyes grew wide by his sudden question. A part of her wanted to chat about this later because, this wasn't the time or the place for a heart felt confession, but Sans seemed to determined to get an answer from her. Guilt and shame made her look down at her shoes, avoiding his inquiring gaze. There was no denying he knew what she had done, but he was asking her anyways. Then, there was a slight pressure beneath her chin as a pair of bony fingers made her look up at him.

"Let's go to Grillby's. I could uh, use a bite after this." Sans spoke softly, almost sounding like himself after his encounter with her violent carbon copy of herself. The one Jeri thought she had left behind in a different timeline and tried to escape from after a reset, and denied was ever real in the first place, despite the nightmares that haunted her in her sleep from sleeping at Toriel's place.

Jeri didn't get a chance to protest as she saw her carbon copy glitch back into existence, lunging forward with her knife to stab her, but by then, Sans had already teleported them away from Judgement Hall and bought them some time, before the carbon copy could get what they're after. Jeri's soul. Now, they were back in Snowdin, where it was freezing cold with snow coming down all around them until Sans shoved her inside to eat.

"What about-?" Jeri started to ask, worrying about the monsters in the underground with a psychotic megalomaniac on the loose.

"I could really go for some ketchup." Sans interrupted her, acknowledging everyone in the pub before taking a seat on a stool and ordering the same meal he's ordered hundreds of times before. Not counting the amount of times the timelines had reset. It was the same old dance, the same old routine, because nothing ever changed underground, everyone's memories would be wiped clean the moment Jeri resets the timeline. It left a horrible feeling in his guts, even if he was nothing more than a sack of bones, because he grew more aware of it with every reset she made.

Jeri took a seat next to him and watched Grillby the bartender return with her fries on a white plate. He was sizzling as ever with his flames burning so brightly in that bartender suit of his that she had to look away. If it weren't for the previous resets before, she'd ask the inappropriate question of how he kept that bartender suit on. It was fire resistant, but it didn't matter, not really. Not when her carbon copy will be on its way to kill everyone she called 'friend'. If she hadn't kept resetting, this could've all been prevented from the start, things would've stayed the same between her and Sans until they made it up to the surface like they were suppose to after finding a way to break the barrier. Jeri let out a depressed sigh, picking at her fries until Sans inevitably did what he always did.

"Want some ketchup?" The bottle was held out to her, except she shook her head, knowing he'd drown her fries in it; making it less edible to eat than it already was.

"No thanks."

Then as if on cue, the room darkened and stilled. Jeri held her breath and knew what was coming as she sat there in her seat. Sans rubbed at his head a few times before shifting around in his stool and looking straight at her until she was left with no choice but to do the same. Or they'd be sitting here for a long time with everyone frozen, if she didn't. It made her wonder how long Sans could really stop time for, but this wasn't the time to test that theory out.

"You lied to me... Kid," Sans accused her in a painful tone, looking less happier than he did before. "You told me ya weren't going to reset again, once we got to the surface. I told you to tell me when ya changed your mind. Why, why did you do it?"

"Sans I-"

Any excuse she could make would fall on deaf ears because Sans eye sockets turned black. Jeri knew she deserved to die. That every time she reset was like a slap to Sans face because, he had to relive it over and over again unless she did a TRUE RESET to wipe his memories clean too. She was a dirty killer. She ruined their lives, and now, because she messed with their lives in one timeline by killing almost everyone, her alter ego was after her and finishing the job for her.

And what was worse? Jeri enjoyed it after crushing those monsters to dust beneath her feet. The worn dagger she still carried around had blood on it; left over from that timeline when she went around stabbing every helpless monster in sight. If she had kept going in her fight against Sans, she would've won. Every repeat of 'Slice', 'Hit', 'Miss', and 'Dodge' got her closer and closer to killing him with every reset she did. When Sans told her to 'give up' she almost had, but a tiny voice told her to keep going until she got the outcome she wanted.

And it was right.

Jeri finally got Sans to kneel over with a huge gash sliced across his chest with blood dripping off of her worn dagger. All she had to do was deliver the final blow. Her arm was held up high with the knife glinting menacingly in the air with her hand clasped around its handle as Sans looked on, waiting for it to fall. One more blow and her Lvl would grow with more execution points. Yet, she struggled to commit to the final blow and end this charade of their so called friendship.

"What changed your mind?" Sans asked dryly, growing a bit impatient with her.

Jolting in her seat at the sound of his voice, Jeri's memories of that terrible timeline came to a screeching halt. Sans was analyzing her with a confused expression on his face, and he must of been guessing what she was thinking about because he drained the bottle of ketchup in one gulp with an audible sigh. Not like it would take much guessing on his part to know what she was guilty of to begin with. Her fries had gotten cold and stale, and suddenly, they lost their salty taste too, when she tried to eat one to prevent herself from having to answer his question. Except Sans wasn't having any of that as he tugged the plate of fries away from her.

Jeri swallowed hard around the fries she chewed in her mouth. Wouldn't it be ironic if she started to choke on them? Maybe she'd die from it and then, Sans couldn't force the answer out of her. However, she knew he wouldn't let that happen by letting her choke to death. No, he'd want to be the one to do it himself. Right now, she needed to think carefully about what her answer was going to be, because he probably would dunk her if she said, 'Because I felt like it.'

Inhaling deeply, Jeri used what courage she had left to finally spit out her answer, "Because you're my best friend."


To be Continued

Last edited:
Oct 20, 2009
dancing on sunshine and gingersnaps
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Yay!!! A piece from KK! And an Undertale one at that. From what's been said Jeri has "played" through the game a few different times, going down both the pacifistic and genocide routes. From my own experiences of playing Undertale you captured the feeling of regret of reseting the world extremely well, as well as the regret from killing all the monsters. And then there's Sans, my personal favorite Undertale character. I don't know if you intended for it, but I got the impression Sans is conflicted about Jeri. Like he still sees her as a friend, but hates her because of what she did. Which I'm curious to learn more of why Jeri did went down the genocide route, curiosity I'm guessing. Especially if she did see it all as a game, and she could do whatever she wanted. But if that is the case now she's seeing that her actions have consequences.

I'm really interested where the story is going to go, since there are so many different ways it go. Especially with the different mechanics of Undertale, and how they can all be used. I can't wait for more :)

Lanydx reborn

The Superior Lanydx
Jun 14, 2009
Holy crap partner, you really got into the gut wrenching work right in there! I gotta know what happens with Jeri and Sans.


Staff member
May 9, 2007
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Ahh, I love reading this. It's so well put-together and obviously a writing of love from someone who enjoyed the game so much. You know I'me picky about fanfiction, and you also know I'm very blunt when reviewing literally anyone's writings, so know that I mean it when I say it's very enjoyable and I really do look forward to reading more.


New member
Sep 6, 2015
I'm glad to finally read something from you, too! Really interesting story, I'm curious if it continues with sans, jeri & his copy or other characters will join them in some way. I'm just an Undyne-Fan, but I'll read the next chapters anyway!