Death was a freaking exhausting dance partner.
The Undying
is an Undertale fanfic by Taliax on Archive of Our Own.
With her sheer determination to protect the whole world, Undyne manages to actually stop the human that's been murdering their way through the Underground. Normally this should be the end of it, as the human can reset over their own death like nothing happened in the first place.
But that's the rub: the human doesn't.
This leaves the remainder of the Underground to pick up the pieces and try to figure out how to continue on from losing a sizable portion of the population. But there's still a lot of influential monsters around to bring them hope in this uncertain new era, and Undyne's better prepared to kick butt than ever before!
After all, they've figured out that the human has a co-conspirator who's still at large and ready to cause plenty of trouble.
The Undying contains the following tropes:
- Aroused by Their Voice: While discussing an individual who can perfectly mimic voices, Alphys comments that she'd "recognize (Asgore's) soothing voice anywhere" before promptly getting embarrassed about saying so out loud.
- "Be Quiet!" Nudge: Alphys elbows Undyne to draw her attention to the presence of Monster Kid right as she's about to swear.
- Convenient Photograph: After he's nearly killed by Flowey, Sans is taken to Asgore's house and brought to the room that used to belong to the latter's children to rest up. Sans spots an old family photo on the dresser and recognizes Chara's face as something he's seen Flowey mimic, allowing him to figure out that Flowey is Asgore's son Asriel reincarnated.
- Emoticon: Mettaton reacts to Alphys referring to Asgore's voice as "soothing" by displaying a ;) on his monitor, though the narration notes that had Mettaton had a face he would've smirked instead.
- I'm Melting!: As per Undertale canon, Undyne starts melting due to the sheer amount of determination she's mustered up to stop the human being incompatible with her physiology as a monster. However, Alphys is able to stop her from melting by augmenting her body with a new kind of armor that can handle her excess determination.
- Impeded Communication: Flowey intercepts Alphys' call to Asgore about the murderous human and mimics the latter's voice so Alphys is none the wiser about the interference. The result is Alphys thinking she warned Asgore to prepare for the worst, Asgore not receiving any calls at all, and neither finding out what's actually going on until the danger has passed.
- I Never Got Any Letters: Part of Flowey's assistance of the human's genocide of the Underground is revealed to have been intercepting all phone calls intended for Asgore to keep him oblivious to the human's actions for as long as possible.Undyne: Someone hacked Asgore's phone. He had no idea that the little freak was wreaking havoc until they were already dead.
- Last-Second Word Swap: After Alphys points out that a child is right behind her, Undyne pivots from cussing out Mettaton mid-word.
- Mythology Gag:
- When entering the True Lab, Sans briefly mistakes Mettaton's voice for a siren going off. In canon, mentioning Mettaton's voice in the essay segment of his EX fight has Mettaton say he has a siren-like voice before going "Awooga!"
- Sans asks Undyne if she thinks the worst people can change, then follows up by asking her if she thinks the human could've changed their ways if they really tried; this paraphrases part of his pre-fight speech to said human at the end of a No Mercy Route.
- Not in Front of the Kid: Undyne starts calling Mettaton a smartass, only for Alphys to nudge her and indicate that one of the Dogi's kids is right behind her. Undyne pivots midword to calling Mettaton a "smart apple" instead.
- Pyrrhic Victory: Thanks to how much determination Undyne manifests to fight the human, she manages to take over control of the timeline after they die because she's got more determination than Flowey, the next-most-determined being in the Underground. Sans has no idea what to think when he discovers this; while the anomaly that was screwing around with the timeline for at least three years is out of the picture, it came at the cost of his brother, the lady in the Ruins he shared jokes with, and dozens of other monsters.The resets were over. But they had taken the people he loved most with them.
- Point of Divergence: The Undying splits off from Undertale's No Mercy route when Undyne successfully kills the human while in her Undying form and the human doesn't reset over the death. This results in an Underground that has to contend with the deaths of many people in all its regions save for Hotland, but still has Asgore as a ruler.
- Power Incontinence: After being empowered by her own determination, Undyne is unable to stop emitting magic from her left eye.
- Technobabble: Alphys starts explaining how the metal alloy that Undyne's new armor is made of is preventing her from melting.Undyne: How does this work?
Alphys: Oh! Well! I tested alloys of mettium with determination extracted from the human souls! It’s really interesting, the determination actually forms an emulsion with the metal ions! That emulsion coats the inside of the armor, so it can adhere to your magic and… - Why Don't You Just Shoot Him?: While fighting the human on a bridge, Undyne thinks that the human could probably dispose of her faster if they just shoved her off the bridge. However, the fact that said human hasn't tried doing that yet suggests to her that they personally want to strike her down.
