Spitfire sat at her desk, moaning at the pile of paperwork in front of her, "Soarin, I swear if Rainbow Dash wasn't laid up in the infirmary, I'd put her there myself"
"Oh, what did she do to you?" he said, placing a cup of steaming coffee on the desk of the Wonderbolt leader and looked at the sky high pile of forms on her desk.
"Oh, praise Celestia," said Spitfire, scooping up the coffee and leaning back. "I need this so badly."
"Badly enough to get me one of those thruster units?" asked Soarin.
Spitfire froze, carefully set down her coffee on the table, and put her forehead on the table, "Sweet Celestia, not you too." Her face was a study in despair.
"Easy Captain," said Soarin. "I was only kidding."
"Ever since Crash did her little 'demonstration' two weeks ago, I've been getting buried in requests to join the '2.0' program," said Spitfire, lifting her head off the desk to motion toward the mountain of paper on her desk. "I've got requests for thruster units from every, single, active Wonderbolt, half the reserves, some of the retirees, and even the princesses."
"Woah, wait," said Soarin. "The princesses want thruster units?"
"Yah," replied the captain, "something about being responsible to their subjects. I sent a pair of the smaller units to them."
"Do they know how to, um, 'mount' them?" Soarin asked.
"Well, I sent a set of manuals, such as we have, with them," said Spitfire. "Anyway, not my problem at the moment. Besides, I've got a tower of paperwork to slay."
"Well, I'll leave you to it, Ma'am," said Soarin, turning to leave.
"Thanks for the coffee," said Spitfire. "And just so you know, I've kept a slot open in the program for you since day one. If you really want a unit just head over to Supply and pick one up."
"Yes Ma'am!" exclaimed Soarin happily, rushing out of the office.
Four hours later, Spitfire walked out of her quarters. She had spent three hours battling the paperwork monster that had taken over her desk. Only to declare a truce when the enemy received reinforcements. With that done, she had visited her quarters to begin her own personal training regimen which was, finally, going to include some sky time. She was walking towards the field when she heard a loud crash from inside some quarters she happened to be passing by.
"Soarin', what are you doing?" Spitfire asked poking her head in the door. She watched the stallion, his eyes squeezed tightly shut, trying to back up against the wall behind him. He almost looked to be in pain
"Spitfire! Ma'am! I mean..." Soarin opened his eyes and stood up straight. There was a loud clang on the floor behind him. "It isn't what it looks like!"
"Really? Because it looks like you are trying to fit a mare thrust unit up your butt," Spitfire paced up beside the "at-attention" stallion. She examined the thruster unit on the floor. "Okay, first off, you need more lube on the front, and second, I really recommend you go with a more intermediate unit at first. I believe in you, I mean, if a lean little thing like Rainbow Dash can fit one of those these up her exhaust I'm sure you can. Just...don't hurt yourself."
"Any suggestions on how I can build up to one of the bigger units?" asked Soarin, getting out the container of lubricant.
Spitfire turned and began to trot from the room, deliberately letting Soarin see the base of the biggest butt plug he had ever seen, "You need to start small and work your way up. This is almost the last one I need to train myself to handle."
"Whoa," said Soarin. "They get bigger than that?"
"No," answered Spitfire. "The last one has a magically animated tail that keeps things...shifting, all the time. That trains you to hold a unit in."
"Damn, Ma'am," said Soarin, impressed. "Where do I get a series of plugs to build up to that?"
"Requisitions," said Spitfire. "I made arrangements to lay in a full supply as soon as I could. I can't let my recruits outdo me, after all."
"Okay," grunted Soarin, trying to mount the thruster into himself. "Ma'am, would you be able to give me a hoof with this?"
"No problem, Soarin," said Spitfire, moving to help insert the unit. "Sometimes, I really do love my job."
Meanwhile, in Canterlot Castle, Spitfire's parcel for the princesses had arrived and Celestia was in her private rooms trying to determine the best way to insert the thruster unit into herself. Much to the horror of a guard who had just walked in to give his Princess a message, and had gotten a rather frank view of Celestia trying to slide a long metal object into herself.
"Your Highness, what are your doing?" asked the guard. "I thought those things were experimental."
"They are. But we cannot allow our subjects to take on such endeavors without our approval. If we are not willing to accept the risks, neither should our subjects," Celestia hummed as she slowly tried to work the thruster unit in. She had requested a smaller unit, and Spitfire had provided two. But even the smaller unit was proving tricky to properly slide into place. Grabbing the provided manual with her magic, she found the section labeled, "Insertion."
"In the event the unit proves difficult to insert, it can be helpful to have a partner insert the unit for you," read Celestia. "Guard," said Celestia aloud. "Please go to my sister's rooms and see if she is awake. If she is, ask her to join me." The guard happily fled the room.
That night, a couple of hours after dark, Spitfire was walking back from the officer's club when she happened to look up and see a pair of comets blazing across the sky. One golden, the other silver. Spitfire just stared for a long minute at the paired streaks of light and directed a quick prayer to the shade of Firefly, the first Wonderbolt, that her princesses not clobber themselves into a mountain.
Cruising along in the sky, Celestia and Luna flew side by side with each other. Thrust units pushing the pair onwards, wings spread wide, both sisters had wide, wide grins.
"Enjoying yourself, Luna?" called Celestia.
"Indeed," replied the dark princess. "I cannot remember the last time I enjoyed a flight more."
"HA!" laughed Celestia. "It wouldn't happen to have anything to do with-"
"OUT OF THE WAY, SUNBUTT!" whooped Cadance, passing the senior alicorn pair in a pink blur. "Make way for the new blood!"
"Sister," called Luna, as Cadance pulled away. "Is it on?"
"Oh yes, It. Is On!" yelled back Celestia, as she accelerated from cruising speed to full thrust.
For the next fifteen minutes or so, Equestria was treated to a spectacular light show as three ribbons of colour danced and swerved about each other in the night sky. Lustily propelled on by the thruster units, the three alicorns indulged in an aerial game of Tag as they reveled in the sheer joy of flight. The light ribboned dance of their movements delighting their subjects far below. But even the stamina of alicorns can wane, and by unspoken consent the trio switched their thruster units to standby and glided in formation on wing power alone.
"I have to say, you two are pretty good considering I know you just got your units today, " said Cadance.
"That's good of you to say," said Celestia. "I'm impressed you were able to keep up with us."
"I invented these things," said Cadance. "Besides my research assistant can-"
"WhaHooWoahHooooooo," yelled a purple streak, blowing past the three and heading toward some nearby mountains.
"Thy research assistant is..." Luna trailed off, disbelief in her voice.
"The Princess of Eggheads," grinned Cadance, "Twilight Sparkle. C'mon, let's catch up with her. If she has what I think she has, this should be interesting." The trio of alicorns activated their thruster units and blazed off in pursuit of the fourth. The purple blaze of light was not very subtle, so the three princesses had no difficulty tracking Twilight to a landing high up a mountain.
The three landed a few paces behind Twilight. She was facing away from them, head down. Her wings were still spread wide, her breathing heavy. Twilight's tail lashed back and forth as a gleaming band of metal could be seen connecting her anal and vaginal areas. The wind shifted, and Celestia, Luna and Cadance realized that Twilight wasn't just aroused by whatever thruster she was testing, she was literally dripping in the throes of estrus.
"Twilight," said Cadance, walking up beside the panting alicorn, "is your thruster mal-"
Whatever the pink Alicorn of Love was going to say was cut off as Twilight turned and, swift as a striking snake, covered Cadance's open mouth with her own. The kiss was hard, strong and insistent. Cadance let Twilight plunder her open mouth, instinctively knowing her sister-in-law didn't just want this, she needed this. Twilight had to release the lust that had been stimulated in her on somepony she trusted and could handle it, lest she explode.
Twilight wrapped a wing around the back of Cadance's head, pulling her in even closer. Cadance felt her own passion begin to rise in response to the kiss. Twilight was slowing down a bit, but her lips were no less hungry, her tongue no less insistent. Cadance felt her own mouth begin to work on Twilight's in response. Her own tongue beginning to feel out the unexplored territory of Twilight's mouth. Twilight moaned in response to Cadance's vast skill in comparison to her own.
Cadance took that opportunity to break free of the lip lock, "Twilight, I'm more than willing to continue. But I need to be sure you want this and not the thruster." Twilight looked at her across the intimate distance they were at. Cadance could see the moment in Twilight's eyes when the iron discipline of being Celestia's personal student reasserted itself.
"Not now," said Twilight, with a smile, taking a step back as she released Cadance. "But maybe another time." Twilight looked over at Luna and Celestia. Luna's face was a mix of happiness for her friends and embarrassment at witnessing so intimate a moment. Celestia looked oddly...proud?
"Should we leave you two alone, for awhile?" asked Celestia, smiling to show she was only teasing.
Twilight took a deep, cleansing breath and brought herself fully back in control. "Sorry about that," she said. "I'm testing out the Mark II prototype and its been a...stimulating experience."
"Mark II?" asked Luna. "You have created a more powerful version of the Thruster device?"
"Yes, I have Princess," said Twilight, lifting her tail high. "Have a look." The other three princesses examined Twilight's posterior. Visible was a broad, rounded metal strip vertically connecting Twilight's intimate holes. Halfway along it's length was the round thrust nozzle of the unit. At the top and bottom of the strip, a close inspection clearly showed that the metal turned into a pair of rounded probes buried deep within Twilight's most sensitive openings.
"Twinned collector units," said Cadance, as she ran a hoof along the outside of the unit. "Can the design handle the extra input?"
"Ye-ah-ah-as, yes," gasped Twilight, as Cadance's hoof pushed the probes a little deeper into her. "The design is sound, what happened with Rainbow Dash was a quality control issue. It's been...ah-Ah...fixed." Twilight shot a look back at Cadance, who backed off with a smirk, "We've run into one problem though."
"What's that?" asked Celestia.
"Well, you might have noticed that there is a slight...moisture buildup," said Twilight. The alicorn sisters could clearly see what Twilight meant. The long period of holding herself on the edge of orgasm had caused Twilight's natural lubricants to flow and ooze past the thruster unit and down the inside of her rear legs.
"That can't be good," said Celestia, as she and Luna drew close. "We might be able to help a bit." Luna shot a playful grin to her sister who gave an answering smile.
"Good, because the unit keeps threatening to slip ou-WAHahahahHA," exclaimed Twilight, as the two sisters each dragged their tongues up either side of her unit, neatly lapping up the accumulated moisture. Twilight spun around to face her two tormentors, "You...you...don't DO that! Do you know how close I am to..." She stopped as the sisters theatrically smacked their lips at the taste they just lapped up.
"Strawberries, Luna," said Celestia, licking some leftovers from her muzzle. "Definitely reminds me of strawberries."
"Nay sister," replied Luna, running her tongue over her lips. "More creamy, like the whipped cream on hot chocolate."
"Strawberries and cream," giggled Cadance. "Now I wish I'd had a taste." Twilight just shot her sister-in-law a "don't you dare" look.
"Indeed," said Luna. "But this is only a temporary solution. I have a potential longer term solution, Twilight. If you are willing to let me try it on you."
"Okay, Princess Luna," said Twilight. "I trust you. Go ahead, do it."
"Very well," said Luna. The lunar alicorn ignited her horn and lunar power enveloped Twilight's rear, swirling and blocking the area from view. When the magic cleared away, the gleam of moonsteel could be seen on Twilight's rear. A skin tight, rounded belt of seamless steel was clamped around her just in front of the point of her hips. A connecting band went over her croup, flowed up and around her dock, forcing her tail high, and then down to connect to the top of the thruster. A matching band on Twilight's underside connected the thruster to the anchoring belt there.
"Auntie," said Cadance marveling. "Did you just lock Twilight into a chastity belt with twin probes?"
"What!" Twilight exclaimed. She tried to push the belt off. First with her hooves, then with her magic. The belt refused to budge. "Luna...what have you done to me?" she asked.
"I've solved your slippage problem Twilight," said Luna. "And perhaps given you the opportunity to learn a little more control."
"But you've trapped me in this. You've taken control of me," said Twilight. "You've...captured me." Her voice had dropped to just above a whisper.
"Only because you gave me permission." said Luna. "If you call me 'Moonie' I will release you immediately. Otherwise, perhaps you would like to play a little game."
"What sort of game?" asked Twilight, still trying to get the belt off her. No use, she was well and truly caught with the twin probes of the Mark II trapped deep inside her.
"Hounds and Hare, Twilight," said Luna. "You with your Mark II, us with our Mark I's. Thirty minutes. If we catch you, you stay locked in until sunrise, with the thruster vibrating and teasing you the whole time.
"And if I manage to avoid all of you for those thirty minutes?" asked Twilight.
"Then I release you, and as forfeit I will allow you place a similar device on me," said Luna. "T'is only fair, after all." Twilight smiled. It was almost a no-lose situation.
"Deal," said Twilight. "Thirty second head start?"
"Thirty seconds," confirmed Celestia.
"If you can catch me, you can have me," whooped Twilight as she activated her thruster and rocketed into the air.
"TALLYHO!" was the cry, thirty seconds later.