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Published:
2025-09-01
Updated:
2026-04-19
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72,749
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12/?
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Bonus Content

Summary:

Ten years into their happy ending, Frisk wakes up back in the Underground with no memory of reseting.

A few hours after parting ways for the night, Kris and Susie wake up in a strange new Dark World... again.

Frisk's save file has been corrupted. Kris's soul isn't behaving how its supposed to. And Ralsei shouldn't be here at all.
An epilogue and a story half-told can't coexist without some conflict involved.

Notes:

never have i ever: written a UT/DR fic. and yet here we are.

i intended to write a different one first, a oneshot to get adjusted to the DR characters, but the story of this crossover has been eating my brain and i had to switch focus. deltarune (and by extension undertale) really helped me get through my seasonal depression over the summer and it resulted in me concocting this fic. now watch me shove almost every headcanon i have into it <3

shoutout as always to my friend Fiore, who patiently lets me ramble into discord at them and then proofreads all my fics. also if you see discrepancies between game mechanics and my writing, blame it on the fact that i don't have the reaction time to play the games (bullet hells my beloathed) and compensate with 45min deep dives into fan wikipedias.

(See the end of the work for more notes.)

Chapter 1: Return to Form

Chapter Text

The distant light of the sinkhole is, as it always has been, gentle and soothing as a wake up. The patch of flowers it shines down on bask in its faint warmth, eager for a taste of the surface they’ll never see.

Sometimes, Frisk would linger here until Toriel came to find them. After an especially fraught reset, it was nice to just… rest. Whether the rest was peaceful or not, well. Frisk isn’t sure even a decade later.

And. They definitely don’t have time to ponder it again. Because something has clearly gone very, very wrong.

I am… in so much trouble, Frisk thinks slowly, sinking deeper into the petals of their deathbed. The flowers are large enough to be comfy to lie on, unlike the flat dorm room mattress they’d fallen asleep on last night. Because they’re nineteen, and in college, and very happy to be so.

They swore to never alter their SAVE file again. They swore to never RESET again. To preserve the beautiful future unfolding for all their friends and family, and be worthy of the trust placed in them. Maybe they’ve reminisced fondly about the Underground, but they wouldn’t undo all their growth just to go sightseeing.

Also, now that they’ve gotten to the point of adulthood, Frisk can firmly say they wouldn’t want to go back to being a child.

Is this Chara’s doing? Frisk can’t hear or feel them. Which is normal… in the future anyway. The longer Frisk lived on the surface with everyone, the quieter and more at peace the resentful spirit had become. For weeks at a time now, Chara stays asleep.

Frisk doesn’t think it was them, not with how close to being ready to move on they are. Could it have been Asriel? Somehow??

But Asriel is as happy as he’s ever been. It wasn’t easy to get Flowey out of the Underground, nevermind integrate him back into society, but they’d done together with their family. Asriel was on a roadtrip with the skeleton brothers last they heard; touring natural landmarks and helping test out Papyrus’s new RV (and Sans’s moped).

…What if Frisk did do this? Even if it was accidentally? They’d been thinking about the loops lately, what with the ten year anniversary coming up. What if they’d subconsciously-?

Frisk reaches for their SAVE file, panic making their SOUL shaky. It doesn’t matter how this happened. They can fix this. They didn’t SAVE in the Ruins yet, they haven’t overwrote the future. They just have to go back to their recent save point in the student lounge, then they’ll call Sans and apologize for the scare-

They brush against the option to view their file.

Frisk  LV??  ?:??

??? - ???

❤ SAVE     RETURN

…They may be in even more trouble than originally thought.

A displeased face appears over Frisk, yellow petals dipping down as the flower frowns at them. “Oh, guess you didn’t die,” he says, then visibly arranging his features into something more friendly. “Howdy! I’m Flowey the flower. I was worried you had died , human, since you’re just laying there. I’m so relieved that isn’t the case!”

Frisk gazes silently at the beady black eyes of the flower, at how empty they are. This would happen every time Frisk lingered in the flowerbed, the flower monster getting impatient waiting for the human to get up and start exploring before he sprung his ‘welcome’ on them.

At this point in time, their friend is a shell of who he could be. Who he should be. The malice behind Flowey’s smile is easy to spot; Frisk is too familiar with his manipulation tactics to miss it. They’re also familiar with the faultlines of his psyche.

“Hi, Asriel,” Frisk says softly, so no one can overhear the name. Flowey’s expression instantly shutters.

“Where. Did you learn. That name.” Each word changes the flower’s face, eyes growing angrier, teeth getting sharper.

“You told me it, because I know the real you,” Frisk says, not dishonestly. They hold still as vines begin to weave through the flowerbed, the simmering tension of Flowey’s temper liable to trigger at the first sign of fear.

Flowey is staring at them, searching Frisk’s mask of calm for cracks. Or maybe for something else, because he then asks in a very hesitant voice, “...Chara?”

“No. I’m sorry. I’m Frisk. I’m still your friend, though.” Frisk debates for a moment, then adds, “Chara is asleep right now, but they’re here, at least a little. I don’t know when they’ll wake up.”

Flowey has a blank look on his face, hiding whatever emotional reaction he’s having. Or whatever lack of one. The distance and distortion of his emotions… Frisk understands better as an adult how muddled it makes him. They move slowly as they sit up, watching their friend for the conclusion of what he’s thinking over.

“You’re being very casual about all this,” Flowey eventually says. He smirks. “How many times have we had this conversation?”

“This conversation? Only once. But we’ve had others a lot of times.” Frisk lost count of how many times. (Sans probably has a guess. They won’t ever ask him.)

“So you do have the power to RESET this world,” Flowey accuses. He grins at them, faux friendliness back in full effect. “Oh boy, if we’ve talked enough times you know who I am, you must have discovered everything about this place. Well have you? Did you find every hidden treasure? Did you uncover every secret?” His grin stretches, teeth sharpening and eyes darkening. “Did you get bored yet?”

“I never got bored,” Frisk defends without thinking. They ignore Flowey’s mocking laughter. “I didn’t . They’re my friends, I wouldn’t ever be bored with them.”

“Then you haven’t done this enough times yet,” Flowey says loftily, spiny vines twisting near Frisk’s knees. “Doing the same ol’ patterns again, and again, and again? Anyone would get bored eventually. Start wanting to be more… creative. ” He looks at Frisk for a long moment, then starts laughing again. “And I can see it in your face. You already have!”

Their sins are crawling up their back.

“I stopped looping,” Frisk says, forcing themself back to calmness. Flowey is impossible to argue with when he’s like this, there’s no point in trying. “I broke the barrier one last time and took us all to the surface. I promised everyone would keep their happy ending for good.”

Flowey blinks, then looks around himself with exaggerated confusion. “Hm. This doesn’t look like the surface to me.” He turns a smug smile back on them. “Guess that means you RESET it all anyway, even after your ‘final’ happy ending. How awful of you!”

Frisk balls their fists. “I didn’t.”

“How long did it take? A year, maybe three? How long until you got bored and wanted to go back again, try it a new way?”

“It’s been almost ten and we’re happy, I wouldn’t undo all that just b- I never would, no matter what.”

“No need to lie to your pal Flowey. After all, I did the same thing!”

“I didn’t! I wouldn’t! This wasn’t me!” Frisk swipes at the flower, missing him as he dodges.

Flowey is cackling even as he dives into the ground, reappearing on the edge of the flower patch. “If it wasn’t you, who else could it be?” he jeers one last time, before disappearing into the ground. He doesn’t come back again.

Frisk is left alone in the cavern, where they let out a long sigh. Their heart is thrumming too fast in their ears. They flop back into the flowerbed, trying to even out their emotions. It feels like their child body can’t handle the full depth of how worried they are right now. Everything feels so much more overwhelming than it should; they shouldn’t have been baited so badly.

(…It wasn’t them. They would never do this to their friends. They promised, they wouldn’t break that promise, they wouldn’t- )

“Oh! Little one, are you alright?”

Frisk jolts upright at the sound of their mother’s voice, sending petals scattering around them. The tall and kindly goat monster is at the entrance of the room, already striding over towards them. “Don’t be afraid, child,” Toriel assures them as she kneels, holding out a hand. She smiles with all the warmth Frisk knows her to have, but none of the recognition or love she usually would.

…Flowey wasn’t entirely wrong about them. About their desire to uncover secrets and hidden knowledge. As a child, Frisk could treat it as a game. Earning the love or hate of each monster of the Underground. But that was a long time ago, and Frisk isn’t that selfish child anymore.

Now, the blank slate of their relationships makes a profound agony spread through Frisk’s chest.

(Their SOUL is intact, but their soul is breaking into pieces.)

Toriel makes a surprised gasp when Frisk flings themself into her arms, clutching tight the robes she wears. It only takes a moment for the old monarch to gently fold the scared child into her embrace, hope kindling in her chest that perhaps this one will stay where she can protect them.

Frisk talked to their mom just two days ago. They wished they’d called her last night, even though they’d been exhausted from classes. They have no idea when they’ll be able to talk to her again.

 

-/-

 

Frisk will blame being nine years old again for the crying fit they have. They’ll cut themself a break for it, since the universe won’t.

Frisk ignores the save points they pass, terrified to wreck something worse. Everything else goes as it should; Toriel leading them by the hand, teaching them with the Dummy, re-meeting all the enemies who steadily become friends… Nothing else is out of place. Just the glitched file.

(Flowey doesn’t show up again, but Frisk knows he must be watching them closely.)

Frisk has to take a deep breath a few times to center themself. As much as they want to rush forward and make it to Snowdin as fast as possible, there’s a chance this can’t be fixed. If they can’t just jump right back to where they’re all supposed to be, then Frisk has to make every choice count.

The way back to the future might be the long way around. So everything has to be perfect in order to get there.

Frisk knows every inch of the Ruins and every monster there like a best friend. A decade isn’t long enough to forget the endless time they spent looping through the Underground. They dodge every attack, SPARE every opponent. They compliment Napstablook into submission with poise and accuracy, sending off their awkward friend in no time.

They feel anxious through the whole experience. About the uncertainty of their way home, whether this is their fault, if they’ll really be able to make it from start to finish without a single misstep… But DETERMINATION has yet to desert them, and Frisk concludes their no-hit speedrun of the Ruins with 100% completion.

Toriel blocks the way, just as she always does. Frisk knows the safest way to approach the fight is the tried and true Script, but they can’t help but speak where they wouldn’t have before.

“You don’t have to be scared for me, mom,” Frisk says during their turn. “I promise I’m always going to be alright.” Nothing can kill them permanently, after all.

“All the others promised me, too,” Toriel returns, grieving each and every little life lost. “None of them were able to keep that promise.”

Frisk dances through the volleys of fire, familiar with every pattern Toriel has to offer. The heat reminds them of home. They choose TALK again.

“I wouldn’t be happy here, not for forever,” Frisk says, knowing Toriel would agree eventually. “And you aren’t either. You don’t have to shut out the world, mom!”

“What would I want from a world that would senselessly kill children?” Toriel snaps, flames growing larger. The pattern is full of holes though, showing how emotional she’s getting.

“A future for yourself! And I swear to be a part of it, if you’ll just let me show you how!” Frisk shouts, thinking of the beautiful home Toriel built for herself, of her dream of opening a school coming true, of every amazing year Frisk spent growing up with her.

Their future is far from this moment, but Frisk will get it all back. For her, for everyone, for themself!

Frisk chooses to SPARE.

 

-/-

 

The forest is so quiet. The warmth of their mother’s hug fades quickly in the cold of Snowdin’s weather, biting at the tips of Frisk’s fingers. Their striped sweater is the only thing preventing them from freezing solid.

Well. Now for the hard part.

They wave at Alphys’s camera in the bush, then set off at a brisk walk. The consequences of that action can’t catch them if they powerwalk fast enough. The crunch of snow under their boots is their only companion for a while, the noise swallowed by the dense foliage of the forest. Any encounter in this area will have to wait for them to doubleback, Frisk has to talk to someone first.

The sturdy stick lays across the snowy path. Frisk marches up to it and stomps purposefully, then pivoting in order to face the figure lurking in the shadows.

If Sans is surprised at the break in Script, he doesn’t show it. His expression doesn’t change even as he steps out of the shade of the trees, smile in place and posture casual.

He’s looking at them like he does on bad days.

“human,” he says, the word flat and exactly like the way he used to say it. Sans starts to take his hand out of his pocket. Frisk is already walking toward him. He extends his hand, not flinching at the way they’re speeding up. “heh, you sure know how to greet a new-”

Frisk slaps their palm against his and grips tightly, the whoopee cushion deflating so fast it’s like a gunshot in the quiet.

“I didn’t do this!” Frisk says emphatically. Their friend just stares at them. They waver a little, seeing the grief in the bruises under his sockets. “I didn’t reset on purpose. I swear, I have no idea what happened.”

“...you’re familiar with the ol’ whoopee cushion in the hand trick, huh?” Sans says, ignoring their words. “too bad. you seem enthusiastic about a classic either way.”

Frisk feels frustration well up in them. First Flowey, now Sans too. Can’t someone just believe them? “Sans, I’m telling the truth!”

“you’re already familiar with my name, too. great. we can just get on with things, then.” Sans’s grip on their hand gets tighter, his eyelights gone. “see, i’m a sentry who’s supposed to be on the lookout for humans like you-”

“Sans, please,” Frisk begs, wincing as boney fingers dig into their skin.

“-and while i like to take it pretty easy, my bro has been kinda on my ass to work harder at my job. be a little more proactive.”

“I didn’t do this, I promise I didn’t!”

maybe i’ll start today.”

Frisk gasps as their SOUL turns blue, one knee buckling as they barely catch themself under the weight of the blue attack. They can feel the start of a battle on the edge of their awareness, the borders of it ready to snap into place the second either of them makes a move. Frisk keeps perfectly still, kneeling in the cold snow and meeting the empty gaze of their closest friend.

“I. Didn’t. Do this.” Frisk says each word through gritted teeth. Their lungs feel tight under the pressure of the attack, as well as their kneejerk panic of seeing Sans so angry.

“you expect me to believe that, kid?” Sans asks tonelessly. “we had a good run. but this is where it’s always gonna end up, right? you’re never gonna let us leave. not permanently.”

Frisk hears the sheer desolation in his voice. They’ve heard it only a few times over the years, when their friend let his defenses slip. The longer a loop plays out, the more he remembers of it next time. Every anniversary that passes adds to that potential recall.

Ten years is a long time.

Their lives are so good now. Frisk knows waking up in the Underground- it must have hurt him so deeply.

Frisk will fix this, somehow. They won’t force Sans to relive his future a second time. No more loops , they promised the final time they broke the barrier. Sans had smiled and said, sure, kid, and didn’t believe them.

Trust is so hard earned, and broken so easily.

Frisk forces their shaking legs to stand. The veil of a battle falls over them both. The blue attack is still coating their SOUL, making each movement heavy, but Frisk selects TALK and carefully chooses each word.

“Something is- wrong. With the file,” they say, desperate to defuse the situation but mentally preparing themself for an onslaught. “I was just going to reload back to where we were last night, but it’s gone. I don’t know what’s going on.”

They wait, sweat beading their forehead. Sans has them pinned and could zero out their HP with a blaster if he wanted. And since they didn’t SAVE anywhere, it would set everything back to the start.

Frisk doesn’t think either of them would handle that well.

A long, tense silence. Long enough Frisk starts to worry he’s using a special attack and just didn’t bother telling them this time.

At last, Sans chooses to TALK.

“say i believe you,” he says, eyelights coming back, “then what?”

He brings Frisk’s soul a little closer to his side. His hold isn’t quite as stifling anymore, easing up into a firm grip instead of a crushing one. Frisk stays still and lets him have the comfort of keeping control of the situation.

“Then we work together to figure out what went wrong,” they say, meaning each word. “Look at my stats to start with. There’s something wrong with them, too.”

They wait patiently as Sans takes his turn, feeling a brief ping in their SOUL as the check starts. His eyelights glance at something and he visibly pauses.

“huh,” he mumbles, staring. He releases Frisk and abruptly ends the battle, SPARING Frisk. Frisk ignores the drain of all the G in their inventory.

 

Frisk

LV  ??
HP  ??/??
G  0

 

“you been messin’ with spacetime, reality or something?” he asks with a small chuckle, only a little forced sounding.

“No more than usual,” Frisk replies, wiping their brow as they relax. Sans laughs a little more, before going quiet.

“...sorry, kid,” he says, shoulders hunching as he slouches. “i really jumped the gun on that one. wasn’t cool of me.” With just the two of them in the woods, he’s letting more of his exhaustion show than he otherwise would. Frisk watches the way he drags a hand over his face, pinching at the bridge between his sockets.

They can tell he’s more than just tired, from that gesture. He feels guilty, too. This is also familiar ground; their friend turning his turmoil inwards whenever they have a rough patch.

“It’s fine. I would have suspected me, too,” Frisk assures him. Their words just make Sans glance sideways at them, clearly disappointed.

“you don’t haveta take my shi- shoddy behavior, kid. i shoulda trusted you.”

“You’re trusting me now, that’s all I care about.” Frisk wrinkles their nose. “Also, you don’t have to censor yourself. I’m not actually a child.”

“pretty sure nineteen is still a teenager of some kind,” Sans teases. “‘sides. your mom would have my butt if she caught me swearing in front of you. best get into the habit now.”

“Undyne is gonna make that effort pointless.”

“undyne is also gonna get suplexed for it, so.”

They both pause to remember the time Toriel got tired of politely asking Undyne to stop swearing in front of ten-year-old Frisk.

“your mom’s a pretty rad lady,” Sans sighs.

“The raddest,” Frisk agrees. They stretch their arms above their head, sighing as something untenses in their back. A nine-year-old’s body is so much more elastic than an overly tired nineteen year old’s. They’ll miss having no kinks in their neck when they get back.

(Definitely not enough to want to stay, not even a little.)

“So! Papyrus, puzzles, and then dinner?” Frisk asks, judging with their internal clock for timeline events. Papyrus should be almost here as he searches for Sans, what with them delaying like they did. “I have a Spider Donut to keep me going until then, but I want real food while we brainstorm. Your treat.”

“figure i owe ya at least that much,” Sans sighs, like he ever pays for anything at Grillby’s, above or below ground. Whatever their arrangement for Sans’s tab is, it’s one of the mysteries Frisk has never been able to suss out, no matter how many loops they did.

They both perk up as a trousle starts approaching, the jaunty aura of their favorite cool guy coming up the path. Frisk grins, before smothering the expression into neutrality. They see Sans take on a perfectly casual posture and cheshire grin.

All the actors are in position. It’s showtime.

 

-/-

 

You blink at the light in your eyes.

You blink at the light…

You… blink…?

Kris blinks at the light in their eyes.

…They slowly sit up. By themself. They feel the soul in their chest, pulsing contentedly, but not even trying to take control of their motions.

A small field of golden flowers bloom around them, basking in the spotlight cast by a high up hole in the cavern’s ceiling. Ancient pillars line the room, vines growing up their stone. The air is warm from the distant sun, but musty from the age of this place.

Kris shifts, feeling the soft petals crush under their gauntlets. They look around themself- unnerved by how little resistance the soul is giving them.

Susie is asleep next to them. Ralsei is on their other side. Susie looks… off. Kris frowns as they realize the girl is dressed in her Dark World armor, but colored like she’s Aboveground. (But… then how is Ralsei here?)

They tug at their bangs, checking the color of themself. The dark brown of their hair means their skin under their armor is tan, not blue.

* Something is different.

Kris thinks the happy pulse of the soul is a bad sign of what’s to come.