~Warning~
Minor lime, I'll put another warning before it and a summery of what happened at the end

Y/n's POV

You went over to Mettaton's and Alphys' for the day, you hadn't seen them for awhile since you had been with Grillby most of the time

As you knocked on the door Mettaton came to open it. "Why, hello, Darling! Its been awhile, hasn't it"

"Yeah, it has. Alphys wanted to show me a game and thought I should come over "Oh... She hasn't stopped talking about the game... Come in!" He smiled at you and stepped aside to let you in

As you walked in you heard someone - it sounded like Alphys - call from the main room "We're here, Y/n"

You headed to the main room with Mettaton, wondering what she meant by 'we're'

You then saw papyrus and Undyne there, smiling at you

Once Alphys explained the rules to you you began playing Truth Or Dare

You had just witnessed Alphys getting sexually tortured from a dare. "Truth"

"How many times have you and Grillby 'done it'?~"

"Is this sexual torture or sexual question or is it truth or dare?"

"Just answer!" Alphys whined

"Fine..." You held up a two sign and looked to Mettaton "ok, truth or da-"

"Only twice??? For Grillby?" "Alphys, he might actually be in love this ti-" Alphys interrupted Mettaton "I'll believe that when he hasn't fucked at least 5 girls this month"

"Actually, he's only fucked 1 since I've been around..." "Oh my fucking god... Y/n congratulations, you've gotten the flame to fall for you..."

"I'd be glad to babysi-" you cut Mettaton off, blushing insanely "not that fast, Metta!"

"She's right, he'd have to pop the quest-" you now interrupted Alphys "I think thats also too fast, now shut up please"

Author~Chan's POV

Would you guys like him to? :3 (I will have to end the book there but I might do a sequel)

Y/n's POV

"Oh, come ON y/n..." Mettaton hid her face while Papyrus was smirking

"What? Its only a-" "NOITISNOT, NOWQUITIT" you couldn't help but laugh at Mettaton's reaction

"oh, Metta... Your reaction was priceless... But! I still want you to do the dare"

Mettaton grumbled and kissed Papyrus "sorry, hun..." He then grinded on Papyrus, them both moaning slightly

"See? That wasn't so bad" Mettaton didnt reply, just get off Papyrus and blush

~Time skip~

Alphys was texting on her phone, a few minutes later Grillby had came to the lab and, after being greeted by Mettaton, came to play the game

"Y/n?"

"Grillby?"

"Welllll, we've got our boyfriends/girlfriends here so we thou-" "ahem, YOU thought" Mettaton interrupted Alphys "I thought that you should have yours..." You blushed and he just sat next to you as Alphys explained the rules

~Time skip~

"What?!"

"Plllleeeaaasssee~" Alphys whined

Grillby grinned, pulling you closer "and she can do it with me" you felt slightly better about it

"No, she'll have to do it with Papyrus"

"WHAT?!" You, Grillby, and Papyrus said in unison, Grillby sounding the angriest

"I'm joking, of course you'll do it with Grillby"

We had made a rule so you can't just say 'have sex with/fuck <Insert Name>' but things could lead up to sex

"I will NOT do that..." "Maybe we could switch it aro-" "OK FINE"

You sigh and go over to Grillby

The dare was to try and make him call you a sexual name (mommy, master etc), but his pants and boxers must stay on so fucking was off the table unless he started fucking you

⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠

First you kissed him, starting off slow and he just smirked, kissing back

Then your hands trailed under his pants, still keeping them on, and massaged his member softly, earning a few moans from him

Once you thought of something to do you broke the kiss and took your hands away, unbuckling his belt

"Eager, are we?~"

"Y/n, you can't take off his pants"

"Never said anything about the belt~" you then tied it around his neck, making it into a makeshift collar, and brought his face inches away from yours

"Your mommy's little pet~" his eyes clouded with lust "mm~... Fuck me, mommy~"

And with that you undid the makeshift collar and gave him his belt back

"Dare done"

"Well, won't you be getting it tonight?..."

Author~Chan's POV

Summary for those who skipped the lime:

Y/n kissed him and massaged his thing under his pants and stopped after awhile, taking his belt off and making a makeshift collar with it and saying 'your mommy's little pet', making him aroused he asked for 'mommy' to fuck him and she undid the makeshift collar, pretending like it never happened

There's the short version!