For the Papyton, I could not use anything else than nsfwshamecave's amazing Underlust AU. I am not quite satisfied with what I wrote but I hope you will at least find it correct.
Three knocks on the dressing room's door resonated between the beige walls as Mettaton wearily sorted his mail. He looked up and felt the mechanism in his throat get slightly stuck for a second before he could clearly pronounce "Yes, come in!"
The panel turned to let inside a certain skeleton whose pink magic shone under the sexy leotard (or whatever it was called) griping his ribs. He closed the door before offering the robot a large smile and a little red rose bouquet he held under his arm. "Good evening, Mettaton! You were particularly charming, tonight!"
"Thank you, Papyrus." He smiled gladly as he took the bouquet. They had been dated for a couple weeks now. Papyrus would often come to see his show and brought a present for every occasion, which almost bothered the TV host.
"It's embarrassing, I don't know what to give you in return."
"Well, you are already giving me your time, that's way enough for me." Stated Papyrus, which made the robot giggle. "Do you have a vase?"
"Ah, I think I do." Mettaton said. His eyes flew for a second towards the wardrobe before getting back to his prince in shining armor. "Would you be a dear and take them for a second so I can go get it."
"No, no, I'll go for you!" said Papyrus enthusiastically. "The wardrobe, right?"
"Uh, yes, but please…" Too late, Papyrus had already opened the door and fell silent when he saw the impressive collection of items stored there. General knowledge books, of course, but also sparkly microphones, dance shoes, cooking tools, as well as all sorts of costumes neatly aligned on their coat-hangers. He even spotted several of his gifts, including the golden bowtie he had brought him on their first date. "Wowie, I didn't know you had all this!" he exclaimed, enthusiast, as he looked for the vase he ended up finding under a large blue-checkered tablecloth.
"Oh, those are mostly old things I picked up before my first show, nothing important…" Mettaton said softly as he put the flowers in the pot. He didn't have water, of course, he'd go get some later.
"You were going to use them on screen?"
"Well yes…"
"Great! But, uh… Why cooking tools? For a Quizz Show?"
Mettaton sighed, slightly embarrassed. "Let's say that, originally, I was seeing much bigger. I was thinking one day I'd have several shows, not just a quiz show." Papyrus scrutinized him as he sat down, smelling the interesting confession. Mettaton smiled and started to talk with a little bit more confidence. "Of course, I love to present my quiz show, but I also wanted to host a cooking show, or maybe something grand, dancing, singing… Maybe even the news! Who knew?" He laughed a little bit. "I had picked all of this for my dreams of future performances. It's ridiculous, I know."
"Not at all!" Papyrus exclaimed, eye sockets filled with stars. "There is nothing wrong in thinking big! And as surely as I will one day be a part of the royal harem, you will one day be on every channel, I have no doubt about it!"
Mettaton had a soft smile, a thank-you slipping past his lips. Papyrus got up to close the wardrobe's door but spotted an item that made him change his mind. "Oh, what a beautiful dress!" He gasped, taking it off the hanger. It was indeed a beautiful dress made in blue sparkling silk with a round and puffy skirt falling down to the ground. Mettaton's eye widened in surprise.
"Oh, this, I wanted to wear it in a musical."
"It'd look great on you."
"I know. But I don't want people to see me in this, I'd draw too much attention. In the bad way."
"I understand." Simply said Papyrus as he tried not to show too much regret. After what the robot had endured, he knew appearance was a touchy subject for him. However, as he tried to put it back, he felt a metal hand holding him back.
"If you… I mean, if you want to, I could try it one quickly, since there is no one here…" pronounced the robot who'd be red like a cherry had he had blood vessels.
"Are you sure?" said Papyrus, letting a spark of excitement slip through his voice.
"I'd like to see if I still look alright in it…" the robot shyly admitted.
Papyrus held out the costume and when he drew closer to take it, bent down to offer a tender and innocent kiss. "You'll always be beautiful, no matter what. I'm sure one day, you'll be the brightest star in the Underground."