((Prompt: A thinly veiled FlutterPie.))
“I just think it's so wonderful,” Rarity said, waving her teacup in her magic grip. She steadied the cup as a bit of liquid dribbled over the edge. “I mean, any time somepony finds somepony else in this life that truly makes them happy, that's cause for celebration, don't you think?”
Twilight Sparkle yawned and nodded, holding her own teacup in her hooves. Her mother would have chided her for not being polite and using her horn, but she was tired and did not trust her magic to hold steady enough. “Yeah, it's great news.”
Rarity took a napkin and carefully wiped up the minor spillage her gesturing had caused. “I'm so happy for the both of them, I really am. They're perfect for each other, really.” The library's firefly lantern flickered yellow as she took a long sip from her tea. “I mean, at first glance, you wouldn't think it. What with all of Pinkie's... Pinkie-ness, you would expect she might terrorize a timid pony like Fluttershy until she was a quivering wreck.”
Twilight let the bitter taste of the tea rest for a while on her tongue. It wasn't like she spent a lot of time thinking on the subject, but if somepony had asked her which two of her friends were most likely to have fallen for one another, Pinkie Pie and Fluttershy would not have been her first guess.
“...But she's really quite gentle with her,” Rarity continued. “I think it's rather sweet. It's clear Pinkie cares for her a great deal.” She drained the rest of her cup and reached for the teapot. “Oh dear, it's empty. I don't suppose you have any more somewhere, darling?”
“I'll brew up some more,” Twilight said, setting her teacup down on the table and seizing the empty teapot. “Again,” she added under her breath.
Rarity smiled gratefully. “You are ever such a gracious hostess, my dear. Thank you.”
More boiling water, another scoop of that blend Twilight had been enamored with ever since Zecora had introduced her to it. A few minutes to steep and cool, and a fresh batch of tea was ready to be shared.
Rarity winced as she took a sip that was still a bit too hot for her. “And their colors go together so well, don't you think?”
For all Twilight knew about colors, Fluttershy and Pinkie might have been pea-green and bright purple and she would still have nodded in response to Rarity's assessment.
“Pink and yellow,” the fashion designer said. “Such a grand combination. I think I shall have to incorporate it into next season's fashion line.” She put a hoof to her chin. “Something flowy, I think.”
Another yawn crept up on Twilight. Being an alicorn did not lend her any super-equine stamina, and she could hear her bed upstairs calling to her.
“They'll of course have to let me make dresses for them to wear on their next date,” Rarity said. “I already know what to make. They're such a charming couple. I... oh my, I'm sorry, Twilight, am I keeping you up?”
Twilight shook her head. “No, I'm...” she stifled another yawn. “...fine. But are you sure you're okay, Rarity?”
Rarity pressed a hoof to her chest. “Me? Why, of course I'm okay, darling.”
“Are you sure?” Twilight asked. “You aren't jealous?”
“Ha! Hahahaha!” Rarity laughed loudly. “Jealous? Oh, goodness no! What in Equestria would give you that idea, Twilight?”
Twilight took a careful sip from her tea. “Other than the fact that you showed up at the library at one in the morning, and have been going on nonstop since then about how wonderful of a couple Pinkie and Fluttershy are, and how you hope Fluttershy isn't too busy with her new fillyfriend to remember your spa dates, and how you wonder if maybe Pinkie is putting on a bit of weight, and that one weird tangent you went on about how Fluttershy's eyes are like tourmalines at the bottom of a very still pool of water? Other than that, no reason.”
Rarity's ears sagged a fraction of an inch. She took a long gulp from her teacup. A silent pause filled the library. At length, Rarity finally coughed to clear her throat. “That's... that's ridiculous, darling. I'm not...” She stared into her now empty cup. “...I'm not jealous.”
Twilight took a deep breath. Though her bloodshot eyes cried out at her for it, she reached out and refilled Rarity's cup for her. “Do you want a cookie? I think I have some in the kitchen somewhere.”