Disclaimer: Undyne is wonderful and I love her, but this was written for the sake of that one ending which I don't see people talking about very often. You know the one.
Figureheads
(Remember your orders, Papyrus? ...That's right. Just stand there, and look cute.)
Papyrus salutes Undyne when she walks past his post in the hallway and asks him how he is.
"Aha, I've never been better," he declares with a hand to his chest. "After all, my brilliance can only grow as each day passes!"
Undyne curls her lips up at him. There is a small but unmissable beat of silence, and Papyrus raises his brow ridge ever so slightly. The gesture asks her wouldn't you agree, but the timing says why aren't you answering?
"That's right." She forces a laugh, realizing she's forgotten her helmet is on. "Hard at work, yeah?"
Papyrus nods. "I hope you are doing well too, Undyne. That you have never been better."
"I'm fine." As long as you are, at least. "Remember your orders, Papyrus?"
"Just stay right here, while you go out and try to destroy the human. And all the other humans."
"That's right."
Undyne doesn't expect many things to be the same, but Her Most Important Royal Guardsman nods just as he used to in his lessons under her. She clears her throat to clear an unpleasant sting in the back of it, before she tells him: "But hey, Papyrus? If I let you, though I obviously can't allow this to someone so important— Would you want to go after them? Get your hands on them and bring them to me, like you used to try?"
"I... certainly would like to get my hands on them, yes! Though I'd rather not take off my gloves."
"Good," she snorts, and slams her gauntleted hand onto his shoulder for old times' sake. A yowl of shock leaps from Papyrus's mouth as a mole leaps from its burrow, and hides away just as hurriedly under his usual cackles.
("Remember your orders, Papyrus," she's told him countless times.)
Sans knows who they did in.
He doesn't tell Undyne, but something clicks when she goes to check on the lazy sentry. When she discovers he's strayed from his post as he always does. He greets her just as she's about to drag him back by the hood, and says he's practicing some jokes. Does he expect someone to come through that door, she wonders aloud— and she realizes. He recognizes her epiphany with a chuckle, so immediately that Undyne could have sworn he was one beat ahead of her.
Sans still doesn't say much, not even the name of whom he imagined was behind the door, only that "In hindsight, it seems like she knew this would happen," and he is as solemn as Undyne's seen anyone with a frozen grin ever be. "'S no way to end things," he murmurs, shuffling some slush with the tip of his shoe.
Undyne hears him loud and clear through her helm."You're saying she wasn't afraid of them," she replies through gritted teeth.
Sans shrugs. "I dunno. She did sound kinda worried."
"She overcame her fears, then. That murderer came to her, and she stood there to fight."
"Heh. Yup, I guess that's how it went down."
A lesser monster would have shook Sans, and only if they had decided to spare his teeth from their fist. A lesser Royal Guard, a lesser Undyne would have drilled into his skull that he wouldn't be laughing if the human had chosen to reveal their true nature in front of Papyrus instead of concealing it — or had they taken their deceit of Papyrus to the same lengths they had with that one little kid they fashioned into their shield— But she knows that if they had, she herself wouldn't have felt much better.
"Just keep sending those reports," she growls.
"Will do," says Sans, with his hands in his pockets and his eyes on some patch or another in the snow. He doesn't know how much contempt brews in Undyne's soul for the part of him that can be this way— but he too is a monster, and his heart beats for freedom like anyone else. So she lets him be.
"Oh, and hey, Undyne?"
She stops in her tracks, caught by surprise.
"Thanks again about Papyrus. Think it's a good gig myself. Bet he's getting used to it already, right?"
"Of course he is," she barks at his back, which is receding into the woods before her.
("Remember your orders, Papyrus?"
"Stay here, just like this, because there are people whose lives depend on it!"
"And don't you dare stray from your post. Don't you move a damned inch.")
Undyne had screamed when she saw the footprints in Asgore's dust. She had dropped to her knees to collect what remained of the king, but ended up banging her fists against the ground as she roared at the barrier to curse the human, to curse mankind, curse Asgore, curse the Guard and curse their Captain, curse her legs failing her in the heat, curse the feeling of water running down her face, so cool and fresh it made her sick. She had tried with all her might to curse Papyrus as well, throwing off the shoulder he offered her whenever she stumbled back into her room, epithets cascading from her tongue. The door of her face-shaped home bared its teeth at him for her, and yet he stood still as a rock right beside it.
It was in that moment she knew what he ought to make of the rest of his life. As long as she lived, at least.
She gorged on tea once she was inside her locked-up house. No matter how hot the stuff was, she discovered, its burning sensation ceased to be once it went past her throat. What was more, she always found it needed to taste different, better, than what she made. She took to either letting the teacup go dark with the flowers' essence, or pour the scalding water into it and drink the weakest brew there was. Either way, it wasn't meant to be drunk like that. Asgore would not approve. Then again, she was no Asgore, and nobody was there to stop her.
She almost takes Asgore's trident when she stands before the crowd; her cadre of Royal Guards, surrounded by a ring of citizens. Here they are, the people looking to the replacement of their King, which she is not. For there could be no King of Monsters but the lost Asgore. For his mantle is not hers to take up. Those eyes she remembers watching so many grow older— her, Shyren, Napstablook, the flowers— are nothing like the eyes she sees the world through. For a King bows his head ever so slightly when he speaks about human souls, and only when his subjects ask about them. She lays the trident among the flowers, and meets the gathering with her trusty spear pointed towards the heavens. She hears the beat of all their hearts, the churning of all their magic. The Underground is still alive. She, Undyne, will make it more so than ever.
"Sunlight," the Empress tells her people, "has been taken from us once more." Her words are stones she casts into the surface of muted silence her comrades make. She is there to make it ripple. Much greater things will happen soon.
"Everyone! Though our hearts are hurt, they are unbroken— for when we come together as a whole, we are unbreakable!"
When her words are swallowed by the waters, they will sink to the floor that is the collective spirit of monsterkind.
"We can bear the weight of sorrow, all the way through the road to our promised glory!"
Any moment now, the floor will start to rumble. The water will rise in the greatest of waves, breaking through all that binds them, sweeping away the enemy and all their monuments, all their history, all their Souls.
"And we will never rest, until the day we reclaim what is rightfully ours!"
The monsters' voices roar in unison as Undyne begins to imagine it.
(It's a job just for you. It's what you've always wanted. So please, for the love of God, Papyrus, shut your mouth and at least look like any other warrior who'd rip a human in two. Do it for me. )
"It's all lies, isn't it, Alphys?"
The scientist jumps; Undyne's voice is shaking as her fingers dig into the illustrated tome of human lore she holds.
"These stories of Heroism. Passion. Compassion," Undyne spits.
"Well, I think— it's more a m-matter of them, uh, t-throwing those away? Or rather, putting it aside, I mean. They're c-capable of that too, just like, like... Anyways! Let's move onto those reports!"
Briefing sessions hadn't been a part of Asgore's routine, as Undyne had found out. But she needs them to consult someone with the brains for politics, to put her helmet down for an hour or a half for a drink, and to see that Alphys is still alive and well. Which she is, thank god, though she washes her hands far more than Undyne was used to seeing nowadays.
"Anything bothering you?"
"I'm not... Er, j-just that Mettaton'll be back online soon, see..."
"Oh, that."
"But he— he'll be totally under control! Not a c-corrupting influence, like you said. Not at all! I just don't want to be around him when he finds out about these—these new laws. Which are perfectly reasonable, by the way, I mean, we're at war, and..." Alphys trails off, looking straight through Undyne.
"My God," she whispers. "We're at war."
"We've always been," says Undyne.
Hotland is managed perfectly, the machines running at full capacity and its resources available to the Guards, the Royal Scientist assures the Empress in these meetings. Meanwhile, Undyne waits for good old Alphys to say something that isn't a formality. But when she finally does, it's something like: "I don't think that much tea is good for you."
"Then what'll I drink instead, soda? I can't. I just can't. Everything else tastes like the damned filth it is."
"Oh, of c-course! I'm not one to talk, I-"
Alphys' laugh is drier than ever, and it is only when Undyne sees her face is contorted in sorrow that the Knight slaps herself on the forehead. She pours the last of the fizz from the bottle right in front of her into Alphys' cup herself, sighing: "'M sorry. Really am. I know you have problems with that tea. I just miss him."
"I know, I know..."
Alphys' claw hovers in mid-air above Undyne's hand, until it grabs her pointy yellow teacup and brings the drink to her lips.
And now for yet another public service announcement.
Adjustments have been made in the Royal Guard Training and Recruitment Process, which now includes an exercise in building resistance to human propaganda. Doctor Alphys, who provided her personal collection of historical documents for the occasion, asserted that viewing these materials would "totally turn them against humans, forever!" And you should trust her on that as much as I do, folks.
So go ahead and sign right up, dear viewers, or recommend someone you care about for the Royal Guard! Take it from me when I say nothing is more important than running a well-oiled murder machine. After all, Mercy Is For The Weak, and our glorious Underground is anything but. Isn't that right, Empress Undyne?"
"No human can make it past Undyne," some of the monsters begin to say over time. They say so out of confidence in her, unless they know about the one who got away— Papyrus, Alphys, and Old Gerson, who doesn't say anything bad about her, but seems reserved as of late. Some of the others swear upon their life to help her; she feels the urge to counter their words by telling them they are to help themselves.
No human can make it past Undyne in order to reach the Surface, but rather that no human should. It is not them who journey through the Kingdom of Monsters to find her, it is Undyne who will come to meet them and end their journey there. For she is no Asgore. She is no Queen. She is Empress. The Underground is her Empire, a wave swelling with the forces of monsters' Souls that will break through to the surface and drown humanity—Yes, to hell with humanity, and to hell with the horrors written in the ancient lore about them! This what she says as she prepares for the next human, as she hones the blades and minds of herself and of her people. She makes sure all of their eyes, all of their ears recognize the enemy quicker than ever before. That their voices will reach her immediately should they call for help, and they will be ready.
Undyne's suit of armor doesn't tremble when she hears the report at last. She'd donned it for this moment long ago.
She hears their cursed heart beating as she approaches them, but she doesn't hear them cry out her name, only the crackle of magic and the spears cutting through the air.
She doesn't feel the human's barrage of kicks and bites and slashes, only the steady decline of their Determination as opposed to hers.
She sees the soul she has captured.
She sees the monsters she will free.
She sees the empire she will lead. She sees the great rising tide.
She sees the stripes of purplish pink around their chest before they collapse.
Undyne stares at the body in the howling wind— Human remains don't disperse, at least not as quickly. Right. Among the ichor and viscera is the human's Soul, glowing with Determination. Acid swirls in Undyne's stomach, but she forces down the sick. She grimaces; Papyrus would be mortified at her state. Stay poised. Stay dignified. She reaches for the Soul, and puts it in its rightful place which Asgore prepared. Gerson would be so proud.
Her wounds sting. Her head is spinning. Yet, there's such a strange warmth in her heart.
The wind carries the scent of golden flowers. She takes it in with her deep, deep breaths, and there it is! The taste of tea, fresh yet nostalgic, sweet yet bitter, all but intoxicating. The taste she has missed all this time, returning to her!
Undyne laughs. In spite of her injuries she is still alive, walking to the throne. The pollen of the flowers there glimmers in the light; it is a sight to see. As per her orders, everyone is there to share it with her. She grins behind her scowling armor, and holds up the container. Look! Look at what our Determination can accomplish! Papyrus! Alphys! Asgore!
The throne room buzzes with occupants' harsh whispers, and Undyne hears their pulses quickening. Were they worried about her? They shouldn't be. She will not die until she finds them again. She will chase them to the ends of the earth, for she is Undyne, for she is Head of the Royal Guard, for she is Empress—!
Papyrus gasps; Alphys drops to her knees, blubbering in horror.
Phasing in and out of her sight like a darkening crystal, like the twilight beyond the Barrier, is the long, white arm Papyrus extends towards her. She gives a boisterous roar at him to stay back- remember your orders, Papyrus, just stand there, let me worry about everything, don't you ever stray.
But he disobeys all of it. He's yelling about how horrible she looks. She laughs harder than she has in such a long time, and takes off her helmet; She needs to look at him face to face, to let him know how great she's feeling.
"Oh, Papyrus, I've never been better than this."