Undyne smirked to herself as she strolled into the Gaster residence, RG 01 and 02 close on her heels. Not that she needed the muscle, but appearances must be kept up. Her smirk turned into a full on grin when she saw who was stalking down the stairs to greet them.

"Hey, punk! Why is the brother of the Don himself here to greet little old me?"

The younger Gaster brother snorted, "YOU SAY THAT AS IF YOU AREN'T A DON YOURSELF AND DUE THIS KIND OF RESPECT."

"Yeah, yeah, I remember what you were like as a babybones, don't try to play uptight with me!" Undyne pulled Papyrus into a headlock for a noogie, it quickly devolved into a loud, friendly wrestling match. A gentle cough from one of Undyne's bodyguards pulled them out of it.

"RIGHT, NOW IS NOT THE TIME FOR TRIPS DOWN MEMORY LANE." Papyrus straightened his tie as he spoke, "MY BROTHER IS WAITING IN HIS OFFICE." He carefully smoothed down his sleek, perfectly cut suit before leading Undyne up the stairs. They fell into step, Undyne's bodyguards trailing behind at a respectful distance.

"Maybe after this meeting we can spar, just like old times!"

Papyrus's fangs curled into a sinister smile. "PERHAPS."

They walked in silence. Undyne wasn't going to have any of that! "So how've you been? I haven't seen you in months!"

"SANS HAS KEPT ME BUSY, WE HAD TO DEAL WITH THAT MESSY ISSUE WITH METTATON."

"Yeah, I heard about that. That uppity robot has always been too big for his britches."

"PERHAPS HE WOULDN'T BE IF A CERTAIN DON DIDN'T KEEP BEING SO LENIENT ON HIM FOR HER LOVER'S SAKE."

Undyne snorted, "The same way a certain Don's certain younger brother isn't just as lenient because of his HUGE crush on a certain uppity robot?"

Papyrus sputtered, "I MOST CERTAINLY DO NOT!" in outrage.

"Puh-leeeeeeeze, I've seen the way you check out his gams. I don't blame you, Alphys does some good work."

"JUST BECAUSE I CAN ADMIRE THE MECHANICAL ENGINEERING THAT WENT INTO MAKING METTATON DOESN'T MEAN I HAVE FEELINGS FOR THE SOUL HOUSED WITHIN. I SERIOUSLY DOUBT ALPHYS'S TASTE, JUST LOOK AT THE PERSONALITY SHE PROGRAMMED INTO HIM." Papyrus stopped in front of a very impressive, very solid door. "HERE WE ARE, SANS SHOULD BE WAITING FOR YOU."

"How is the little shit?"

"HE'S BEEN WELL, IF A BIT DISTRACTED. I'M SURE HE'LL BE EAGER TO SHOW OFF HIS LATEST… ACQUISITION TO YOU."

"Oh? What'd he get?"

"I WOULDN'T WANT TO SPOIL THE SURPRISE." Papyrus winked audibly, and he said he didn't like Mettaton's personality. Clearly the problem was they were too alike.

"Alright, I'll ask the pipsqueak myself. Afterwards?"

"OF COURSE." Papyrus left then, nodding to RG 01 and 02 on his way out. Undyne knocked confidently on the door.

"who's there?"

"Undyne!"

"undyne who?"

Undyne rolled her eyes. "You know very well who I am."

"aren't you just a barrel of laughs?" The door clicked, just barely cracking open. Undyne pushed it the rest of the way to see Sans sitting at his desk, framed by the light coming in through the window behind him, head bent as he finished writing something. The office was immaculate, like it always was, which surprised her, like it always did. She'd seen his room back when they had all been a bunch of dumb kids trying to barely make ends meet and dreamed of making names for themselves, it had never been immaculate. She closed the door behind her before flopping into the chair facing Sans, then propped her feet up on the desk.

"hey! git yer dirty ass boots offa my desk, that's real mahogany!"

Undyne smirked as she let her feet drop. "Nice to see you too, and so good of you to give me your undivided attention."

"not my fault these idiots can't keep themselves out of trouble if their crappy lives depended on it. 'm almost done." He signed the paper with a flourish, then folded it up and dropped it into one of his desk's drawers. She'd be offended if she weren't mostly sure it was actually a dimensional box and someone would be pulling it out somewhere else soon. She took the time to look around the office while he did that, to her surprise his prized aquarium had been moved to the corner. All the better to see from his desk, she supposed. That and the wall it used to stand against had been replaced by a new, huge aquarium. You may have read that wrong, so let us just go over that one more time: the whole wall had been replaced by an aquarium. Strangely, aside from some sand, rocks, and weeds, the thing seemed to be empty. Not a fin or shell in sight.

Sans leaned back in his chair and put his own feet up on the desk as he pulled out a cigar, lit it, and shoved it between his sharp teeth, right next to the gold false fang. "so, how're the docks doin'?"

"Great! Who knew being in charge of the waterfront of a port city was so lucrative?"

"anyone ever, 's why ya gotta fight fang an' claw to keep yer territory."

"Yeah, and what a fight it is!" She chortled, "All these idiots who think they can just off one of the most powerful Dons this side of Ebott. It sure keeps me on my toes, too bad it's pretty anticlimactic most of the time, too few of them can put up a real fight. But this latest contender, Muffet I think her name was, what a cunning bitch she's turning out to be!"

"yeah, i've had a little trouble from her too. she knows what she's about, gotta give credit where it's due. someone to keep our eye sockets on."

"Yeah, more me than you. But don't think just because she's more focused on the docks she won't set her sights on… the fuck?!" Motion had caught Undyne's good eye, she glanced over to see something she never expected: an unknown monster. In Sans's aquarium. The wall one.

They seemed to be a fish monster of some kind: a head, torso, arms, and a long tail trailing large, frilly fins. They were a deep indigo, or maybe more of a violet? It was hard to tell with the way their scales glittered. There were red streaks in their fins and a black fringe at the edge of, it would be rather pretty if Undyne weren't filled with horror. "Why the FUCK do you have a monster for A PET?!" She was on her feet, motioning dramatically at the aquarium. The door opened, one of her bodyguards peeked in.

"wow, rude!" Sans dropped his feet to the floor, swiveling in his chair to face the aquarium before scooting inelegantly across to it. "he has a name, you know." Sans put a hand up to the glass and smiled at the monster. The monster put their own hand up, shades (of all things for an underwater monster to wear) pointed directly at Undyne.

"That's my point exactly! He's got a name and you've got him trapped in a fucking aquarium! Is THIS the 'acquisition' Papyrus was talking about?!"

Sans snorted, "don't be dumb, how the fuck could anyone keep a monster trapped without tying them up? he ain't trapped, he can do whatever he wants.

"Bullshit!" Undyne stomped closer, reaching to grab Sans by his expensive lapels and shake some sense into him. To think her childhood friend, the brother of her own best friend, had sunk to monster trafficking! Before she could get to him, however, a line of shimmering, violet flames sprung up between them.

"… Hey bitch, don't you even dare."

Undyne looked up to see the fish had half pulled himself out of the aquarium, sitting awkwardly on the lip with a ball of fire held in one webbed hand. Well that just didn't make a lick of sense.

"awwww… sweetheart, i didn't know ya cared!"

"… We're datemates, you blithering idiot."

"but 'm yer blithering idiot."

Even behind the shades Undyne could see him rolling his eyes.

"What? How?"

"undyne, meet grillby. grillby, this is undyne the undying, don of the waterfront and good friend of mine. i'd 'preciate it if ya didn't grill her."

"… Is she going to back off?"

Sans shrugged, "dunno, are ya?" They both turned their stares on her.

"How the fuck is a fish doing fire magic?"

"… I'm a tropical fish."

"That doesn't… no, not important. Is he or is he not this 'acquisition' Papyrus wouldn't tell me shit about?"

"no? we've been dating for… oh wait. he was talking about the new tank." Sans patted the glass affectionately. "i just got it installed, this baby's got a whole half a wing dedicated to it, plus this and a couple other little outlets in a couple other rooms. i wanna get the whole house remodeled but the li'l bossy bones-"

Undyne snorted, "Papyrus hasn't been smaller than you in years!"

"he hates it. 's why i wanted to see ya personally, actually. i've been looking into houses right on the shore, somethin' with easy access to the ocean no matter the tide, somethin' i can remodel so grillby has access to the whole house. or maybe just build something from scratch if i can find a good property and a good architect. but that'd be in yer territory, so i wanted to make sure yer okay with it." While Sans spoke, Grillby's flames flickered and went out, the monster himself slipping back into the tank until his arms were resting on the lip, his chin nestled in his arms.

"What do I get out of this deal?"

"undyne! i'm surprised at ya!" Sans put a hand to his sternum as he looked up at her with a mixture of shock and betrayal. "i thought we were friends!"

Undyne rolled her eyes, "You make me cut deals whenever I'm asking you for a favor."

"i didn't get to be don of half the city by being soft."

"You aren't Don of half the city though."

"'m workin' on it." Sans flapped a hand before ambling over to his desk. "what wouldja want, anyway? most of the houses i've looked at are on the edge of the city, barely even in yer territory."

"I wanna give a speech at the wedding!"

"what?"

"The wedding! You're buying a house together, you're remodeling this one, clearly you're getting hitched. Right?"

Sans's face turned so red he looked like a cherry tomato. A scarred up, shark toothed cherry tomato. "we ain't… i haven't… that uh…"

"… He hasn't asked yet, though with the way he acts I think I might have to." Grillby put a hand up to his mouth so Sans couldn't read his lips and stage whispered, "… Bottom," while gesturing towards Sans.

Undyne nodded, "I always suspected."

"i hate you both."

"… Yeah, but you're marrying me anyway."

Sans's face turned somehow redder. "i mean… yeah. 'm buying ya a house, ain't i? was gonna use it fer a proposal gift."

"Alright! I'm giving a speech at the wedding! Possibly the best maid speech if you have Alphys as yours. Oh man, she's gonna flip! Wait, does she even know you're dating someone? I didn't, you really kept it on the down low."

"'s not like i was trying to keep it a secret, me an' you've both been pretty busy. bein' a don is tons of work." Sans looked down at his feet, face still so bright he was casting the room in a faint red glow. "an' 's not like i could take grillby on a lot of dates anywhere without water."

"… Honestly, we spent most of our time laying on the riverbank or sea shore talking, skeletons aren't exactly good swimmers. No buoyancy."

"Well I know now! I'm going to have to give Papyrus a noogie or three for not telling me! Anyway, it was nice meeting you, Grillby. Make sure to give me an invite to the wedding and let me know what property you pick out so my minions can be informed to leave it the fuck alone."

"sure, we'll uh… we'll do that."

"… He's so cute when he gets flustered."

Undyne pulled Sans in for a very, very gentle noogie, she knew better than to actually hurt the little goober.