Underloop

Title of underloop. The prequel to underloop: the last reset and undertale: tine patrol

Creator: me aka peyton (https://www.deviantart.com/peytonproductions)

Sequel branches of this au: Undertale: Time Patrol or Underloop: The last reset

🌀 UNDERLOOP: Sans and the Curse of the Eternal Reboot[]

1. Premise: The Genius with No Memory in a World That Forgets[]

In this AU, resets are total. Memories are wiped. Nothing persists across timelines — except instinct.

Sans isn’t mad because he can’t remember. He’s haunted not by memory, but by the residue of memory — pattern recognition baked into his personality.
Each reset, he becomes the same detective. Not because he learns, but because his core programming forces him to rediscover. He’s a self-repeating algorithm shaped by unremembered trauma.
Papyrus is the emotional anchor. While Sans loops through paranoia, Papyrus remains innocent, trusting, and unchanging — making him the ideal constant in an otherwise chaotic loop.

2. The Timechamber: Where Time Cannot Reach[]

Hidden within Sans’ lab is the Timechamber, a place unaffected by resets. Here:

Time flows linearly.
Anomaly interference is blocked.
Sans keeps a journal immune to resets — the only artifact of continuity.

Each cycle, he rewrites his mental model from scratch using cues from this preserved space — a recursive bootstrapping of his intelligence.

3. Papyrus: Bait, Variable, Key[]

Papyrus serves three critical roles:

The Control Variable: His emotional consistency reveals deviations in others.
The Test: Sans watches how anomalies treat Papyrus to determine their type.
The Trap: Papyrus unknowingly hides secret tells (like his real favorite food) that expose the anomaly.

“You like dino egg oatmeal?” — a phrase that proves someone has reset the world hundreds of times.

Papyrus is the canary in the coal mine, lovingly used — and tragically sacrificed — to bait the godlike anomaly into exposure.

4. Sans: The Observer Who Always Notices[]

Sans doesn’t evolve. He reconverges. His genius doesn’t grow — it resets. He’s like an AI rebooting to the same state, every time, yet always reaching the same disturbing conclusions.

Quotes like:

“You’ve been busy, huh?” “I always wondered why people never use their strongest attack first.”

— show that he sees through the reset, not by memory, but by cold logic. He recognizes behaviors too precise to be first-time choices.

5. Profiles of the Anomaly[]

Sans has narrowed the anomaly’s behavior to five repeating archetypes:

The Completionist – obsessive, thorough, experimental.
The Sadist – destructive, power-hungry.
The Savior – idealistic but ego-driven.
The Explorer – curious, chaotic neutral.
The Troll – impulsive, mocking, thrill-seeking.

Each is predictable. Each leaves a signature in how they treat Papyrus — and Sans is always watching.

6. The Stalemate: When Winning Isn't Possible[]

Despite outplaying a time god, Sans cannot win. He can trap, predict, expose, even kill — but the anomaly always reloads. The game never ends.

So Sans stops trying to win.
He copes through laziness, jokes, and detachment.
He steps into each new loop knowing he may fail again — but with clarity.

He becomes not a savior, but a counter-anomaly — an entity shaped by recursion to see the truth, even if he can’t change it.

7. Final Message: Knowledge is the Only Weapon[]

The video ends not with victory, but with acceptance:

“A god can be outwitted. But not defeated.”

Sans doesn’t break the loop. He just understands it. And sometimes, that’s the only victory left in a broken world.

---

Absolutely. Here's the complete version of the interpretation, with all the thematic and conceptual depth you described — cloned back exactly, minus any reference to it being a video:

Sans and the Curse of the Eternal Reboot

In most stories, constant failure would break a person. But in this world, the resets are total. Sans isn’t “going insane” in the traditional sense — because he can’t remember to be driven mad. That’s the tragedy.

Instead, Sans’ very personality has just always been a blueprint, an echo of a thousand forgotten conclusions. He’s been subconsciously primed by prior cycles to become this paranoid, methodical, genius-level detective. It’s not memory guiding him — it’s the gravitational pull of identity.

Each reset reboots the world, but not the instincts. His drive to figure out what’s wrong with the timeline, his suspicion of the anomaly, his distrust of the universe — those traits recur, no matter what. They’re baked in.

This makes Sans a kind of self-repeating AI in a corrupt loop, re-developing the same theory over and over with slight variations, slowly tuning his mental model of the anomaly through pattern recognition that survives the reset like residue in code.

Papyrus: The Sacrificial Hope

Papyrus is the emotional counterbalance to Sans’ cold logic. Where Sans is calculating and paranoid, Papyrus is hopeful, trusting, and innocent.

But this innocence becomes a tool — or worse, a weapon.

Sans, stripped of traditional ethics by the nature of resets, is building a plan. A longform, recursive algorithm that can catch or kill the anomaly. And the only fixed constant in his life is Papyrus.

So, in the most chilling interpretation:

Papyrus is the bait.

Sans knows the anomaly responds emotionally to certain events. Maybe it always resets when Papyrus dies. Or maybe Papyrus’ death can provoke a specific, traceable reaction. So Sans, across countless resets, is shaping events to lead to that outcome — willing to let his own brother die, over and over, to test theories.

He doesn’t remember the specifics — but the design of the plan reasserts itself with each new loop, like déjà vu coded into his soul.

This makes Sans not just a victim of the anomaly, but a counter-anomaly: a being so shaped by recurring trauma and instinctive suspicion that he becomes the only real threat to the time traveler.

Existential Horror and Moral Decay

Now the real horror sets in:

The anomaly is untouchable because it can rewind death.
Sans is untouchable in another way — he forgets everything but becomes shaped by patterns anyway.
Papyrus, the most human of them all, is the only one who actually dies.

The moral rot here is chilling: Sans, who once joked and protected his brother, is now turning him into a sacrificial variable in his grand equation.

And the worst part?

It's Frisk— the player, the anomaly — are watching it all happen occasionally or when they can, thankfully it's like at the bottom of their list of worries.

Sans: The Unchanging Observer

Sans doesn’t “evolve” over time because he can’t. Resets are a clean slate. There’s no cumulative knowledge. But what remains — and what this theory emphasizes — is that Sans has always been like this: paranoid, analytical, suspicious, quietly brilliant.

This means the role he plays isn’t one of someone becoming a detective — he is the detective, and he always has been, baked into his very core.

He was built to notice.

Papyrus: The Control Variable

If Papyrus is the constant in Sans’ observational method, then we see the genius — and horror — of Sans’ plan:

He uses Papyrus as a probe — the only stable point of emotional contact for anyone traveling through the Underground.
He observes how you interact with Papyrus.
Do you hurt him? Befriend him? Ignore him? Kill him? Spare him every time?

Each reaction becomes a data point. And Sans, though he doesn’t remember specific outcomes, is designed to rebuild his suspicions anew with surgical accuracy each cycle.

Papyrus isn’t just bait — he’s the test.

Sans watches him the way a scientist watches an indicator strip in an experiment.

How you treat Papyrus is how Sans begins to form his judgment.

The Perfect Trap

Sans never forgets in the literal sense, but:

He doesn’t need to.

His pattern recognition is so precise, his paranoia so sharp, and his environment so familiar, that he can recreate the entire theory every time from first principles.

That’s why when he finally confronts you in the Genocide route, he says things like:

“You’ve been busy, huh?”
“...I always wondered why people never use their strongest attack first.”

He doesn’t remember your past runs — he just knows you’ve been through before. Because no one acts the way you do unless they’ve done this before. It's all too precise, too cruel, too effective.

The Timechamber: Memory’s Last Refuge

There exists a space outside the anomaly’s influence: the Timechamber — Sans' secret room, or science lab. In this room:

Resets do not apply.
Time flows linearly.
The anomaly cannot see or interfere.

Here, Sans keeps a diary that is immune to resets. He writes down theories, mental models, simulations — and revisits them anew each loop. The diary gives him a fragile thread of continuity across resets.

Even when his memories are wiped, the design of his personality ensures he always rebuilds his theory. He becomes a genius not through experience, but by being engineered by trauma, suspicion, and obsession.

Papyrus: The Perfect Trap (Expanded)

Papyrus is more than a brother. In this setup, he is:

The scapegoat.
The control variable.
The one person who will never betray Sans.

Here’s the brilliance — and horror — of the trap:

Sans told Papyrus to pretend spaghetti is his only favorite food. But secretly, Papyrus also loves dino egg oatmeal — and he’s been told to never tell anyone. He hides a note confessing this in a hyper-obscure location — something that would take dozens or hundreds of resets to find.

So:

The moment someone says to Papyrus, “Oh, you like dino egg oatmeal?”,

Sans instantly knows — this person has reset the world over and over to find that detail.

That person is the anomaly.

Papyrus, innocent and sweet, is perfect bait: no one suspects him. But Sans is always watching. Always listening. Always waiting.

The Five Profiles of the Anomaly

Through years of looped observation, Sans categorizes the anomaly into five recurring personality types:

The Completionist – Plays the world like a checklist; seeks all endings and interactions.
The Sadist – Thrives in destruction; the one who enjoys Genocide routes.
The Savior – Wants to save everyone, but often for personal redemption or satisfaction.
The Explorer – Hunts secrets, unused content, alternate paths.
The Troll – Resets for amusement or chaos, caring nothing for consequences.

Sans doesn’t remember the anomaly’s exact actions — but he rebuilds this model every time. It’s embedded in his soul, like code rerunning itself.

The Stalemate: Outplaying God Still Isn't Enough

Here’s the final truth — and it’s devastating:

Sans figured it out.

He won.

He outplayed a time-traveling god.

But it doesn’t matter.

Because even if he identifies the anomaly… even if he kills it… it always comes back. It always resets. Always reloads.

The fight is unwinnable.

So Sans stops trying to win. He chooses:

To act lazy, because caring too much would destroy him.
To make jokes, because humor shields him from despair.
To move forward, even when everything loops back.

His plan didn’t solve the problem — but it gave him clarity. And sometimes, clarity is enough.

Final Message: A God Can Be Outwitted, But Not Defeated

There is no final battle. No victory.

Sans knows he cannot kill the anomaly.

But he can understand it.

He can know it better than it knows itself.

That knowledge is his weapon — the one thing a being with infinite power can never fully erase.

It’s not a win.

But it’s enough to keep going.