I apologize for this part’s shortness, but the particular style does not lend itself to length. At least not of the story...
Rainbow Dash toweled off the last of the water from her shower. It had been far more fun than she expected to take a shower with the princess, and the warm smile on Celestia’s face indicated she had enjoyed the company. Rainbow wondered if Twilight had been taught any of the many tricks Celestia seemed to know, and decided to make it a priority to get a little one-on-one time with her friend when she returned home.
Suddenly, a letter appeared in front of Celestia. As the princess opened and read it, Rainbow Dash’s mind ran. The paper was obviously specially made to teleport, but it could apparently be used to send things that would normally burst into flame as well, like the Gala tickets, and in this case, a small picture.
“Princess,” Rainbow began. Celestia looked up from the letter. “Can you send packages and such with the magic mail?”
Celestia appeared to understand Rainbow’s train of thought almost instantly. A coy smile spread across her face. “That’s an interesting idea, Dash. Let’s see if it... goes anywhere, shall we?”
In a few moments, Dash was wrapped head to hoof in the special paper. She couldn’t move for fear of it falling off, so Celestia used her magic to carry her over to the fire. Rainbow Dash let the gentle sensation wrap around her tantalizingly, but as she drew near to the fire, she became worried.
“What happens if something goes wrong?” she asked, taking advantage of her free jaw.
“Don’t worry,” Celestia responded. “I wouldn’t be letting you do this if I thought you could get severely hurt.”
“What about slightly hurt?”
“Do you want to do this or not?” Celestia asked, stopping in front of the flames.
Rainbow thought for a moment. “Let’s do it.” With that, Celestia dropped her into the fire, and the world disappeared.
Rainbow was stuck looking into a psychedelic abyss, colors shifting all around her. She felt weightless and her body tingled with a sensation several times stronger than that of being lifted by telekinesis, yet she was suddenly uncomfortable in her locked position. She tried to hold herself steady, but the urge to move finally won over, and the paper over her body fell away as she contorted herself.
Exposed to the open, the sensation became even greater, and Rainbow felt wetness form across her body, especially between her hind legs. She reached down and touched the wetness, and the contact point surged with feeling. She began to rub as sensation surged through her body, the surprisingly slow trip giving her plenty of time to enjoy herself.
Soon, though, she realized that she had been holding her breath, and she found it impossible to breathe. Her body shot with adrenaline as fear set in, but the hormone only made her sensations more sensational. She slowly began to slip out of consciousness as the oxygen in her lungs ran dry, and she rubbed ever harder, her weakened mind assuring her that the best way she could die was in the lap of absolute pleasure.
As she neared blackout, Dash’s body reached its tipping point, and she breathed in sharply as wave after wave of pleasure wracked her body. As her senses returned to her, she realized she was staring at somepony’s legs. She looked up to see Twilight standing over her, mouth stuck agape and eyes wide as saucers. She looked around the room, and looking between her legs she spotted Spike, his face and chest covered in a clear liquid. He shared Twilight’s look, but with the addition of a certain extension standing readily below his belly.
“Um... hi, guys,” Rainbow said as she got up and dusted herself off. “So, uh... special delivery, I guess.”