((Prompt: A time of renewal.))

“Oh, darling, I don't know about you, but I've been needing this all week!” Rarity exclaimed as she and Fluttershy passed through the doors of Aloe and Lotus' spa. “This is always the highlight of my week. Don't you agree?”

Fluttershy nodded quietly. “It's always nice to get together and catch up,” she said. The sweet floral scents of the spa greeted the pair of mares as one of the spa sisters greeted them at the front desk.

“The usual,” Rarity told Lotus. With a smile and a nod, the blue pony led them to the changing room where they kept custom bathrobes just for the two of them. The spa sisters knew how to treat regular repeat customers.

It took Rarity and Fluttershy a few minutes to put on their bathrobes and put each of their manes up in a towel to protect them from the humidity. Rarity inhaled a lungful of soothing steam as they entered the sauna. She sighed happily as heat leached into their coats and relaxed their muscles.

“It's just that I've been dealing with so much stress this week,” Rarity continued. Fluttershy nodded; she was used to her friend carrying on conversations across the brief pauses between phases of their spa treatment. “I've had a few orders from my spring line to fill, including that one purple thing that I just threw up there on a whim. I didn't expect anypony to actually order that one, it just rounded out the color scheme on the display.”

After the spa, there was a reinvigorating dip in the ice baths. Rarity shivered as she toweled herself off. “So I had to go back through all my old designs to try and find the pattern for it. I like to think I'm as organized as the next mare, but, well, some of those patterns are from all the way back when I was a filly!”

“Oh my,” Fluttershy responded, sluicing water off of her wings. “So did you find it?”

Another few minutes were spent wrapping the unicorn in seaweed in preparation for the mud bath before she replied. “You know, I never did. I had to remake the whole design from scratch. Fortunately, it wasn't too complicated, but it was still a lot of time I could have spent filling orders or making something new.”

Fluttershy felt the mud soak into her coat. The minerals set to work restoring health and sheen to her skin and fur. “I'm sorry to hear that,” she said, letting her eyes slide closed.

The mud baths ended. They washed off, put their robes back on, and then the massage tables were next.

“B-but l-listen t-to m-me, I've d-done n-nothing-g but c-compla-ain th-this whole t-time,” Rarity said as an assistant's hooves beat lightly on her back. “H-how have y-you b-been?”

Fluttershy's massage was little more than a gentle rubbing. She made a content noise. “Oh, I've been all right. Angel has been especially well-behaved this week.”

The massages over, they moved onto hooficures. Rarity chuckled as Aloe filed away at the rough edges of her hoof. “If he's anything like Opal, that means he wants something!”

Fluttershy shook her head. “No, I'm sure he just wanted to be extra sweet just as a favor. I think I'm going to fix him a special treat today after I get back.”

“Fluttershy, darling, never change,” Rarity giggled.

Their hooves taken care of, Rarity and Fluttershy were led to a private room in the back of the spa. Aloe and Lotus left the pair of them alone in the sparsely-decorated room, closing the door tightly behind them. There was no lamp, leaving them immersed in complete darkness.

Fluttershy blinked in the dimness. “I... don't remember this part of the routine.”

A pale green light illuminated the room. Rarity's eyes glowed with an otherworldly sheen, revealing a small smirk on her lips. The faint sound of buzzing insect wings filled the air. “No, darling, you never do remember this part...”

...

Rarity and Fluttershy walked out the front door to the spa together. The fashionista took a deep breath. “Ahh, I feel so much better! Don't you, dear?”

Fluttershy swayed on her hooves, and nodded slowly. “Yes... I feel so relaxed...”

Author's Notes:

The trouble with twist endings... how do you tag them? Do you tag them with what the twist turns it into, spoiling at least some of the surprise? Or do you tag them as what it appears to be for most of the story, and then startle the poor readers that had no reason to expect things to take a sudden turn?