In the land of Equestria in an undisclosed room in Canterlot Castle, the mirror portal to the human world rippled as two ponies passed through it one after the other. The first pony was an old, gray unicorn stallion with a long, white beard and mane. Normally, he would be wearing a dark blue wizard’s hat and cape decorated with stars, moons, and jingle bells, but at the moment, he was dressed in a trench coat, a baseball cap, and a pair of shutter glasses decorated with a palm tree and a parrot. His companion was a young, lavender alicorn mare dressed in a crop top layered over a yellow, long-sleeved shirt, sweatpants, a camo-colored, wide-brimmed hat, and a pair of sunglasses with orange frames and reflective lenses.
“Twilight, Starswirl, you’re back,” a small, bipedal, purple and green dragon greeted them as the two of them removed their disguises. “So, how did it go?”
“Well, Spike, Starswirl and I managed to seal the darkness back in Limbo,” the alicorn replied levitating the clothes she had been wearing into a wooden trunk and putting on a tiara with a six-pointed star. “Hopefully, that will be the last anyone sees of it.”
“Hopefully,” Starswirl agreed as he donned his trademark hat and cape.
“By the way, Twilight, Shining Armor is here with somepony he says you need to meet,” Spike added. “He says he’ll meet you in the throne room after he gives the guy a tour of the castle.”
“A tour of the castle?” asked Twilight raising an eyebrow. “Why?”
“I don’t know. I didn’t ask,” Spike shrugged.
“Well, Your Highness, it’s been a pleasure being of service to you,” Starswirl said to Twilight with a bow, “but now, I must be on my way. I still haven’t finished traveling Equestria and learning about its ponies.”
“Oh, of course,” Twilight bowed back in respect before turning to her faithful assistant. “Spike, could you show Starswirl out please?”
After Twilight, Starswirl, and Spike parted ways, Twilight began walking towards the throne room. Her mind began to replay the conversation she had in the human world with her friend Flash Sentry.
“She told me that you’re about to get married to a certain very lucky girl,” she had said to him.
The “lucky girl” in question was Twilight’s own human counterpart, and she and Flash were an excellent match if Twilight could say so herself. Granted, Twilight’s opinion may be strongly biased since she had been attracted to Flash herself once upon a time. Additionally, as much as Twilight hated admitting it even to herself, she may have also been enjoying her counterpart’s good fortune vicariously.
Back when Twilight had first met Flash, both her impulsive side and romantic side had entertained thoughts of possibly having him herself, but her practical side had reminded her that having Flash meant that one of them was going to have to walk away from his or her whole world and she couldn’t be the one to do it because as Equestria’s princess, she had responsibilities that she simply could not walk away from. Furthermore, her selfless side had reminded her that Flash couldn’t be the one to do it either because having him give up everything for her wouldn’t be fair to either him or the friends and family who cared for him. In the end, Twilight had decided to accept the cold, hard sting of reality, move on from Flash, and live her life. For the most part, she had been happy with that decision.
“Except for the occasions when I find myself wondering if I’ll ever fall in love again and if I’ll ever be in an actual relationship that will last,” Twilight thought to herself with a frown. Then, she smiled, blushing slightly as she remembered what Flash had said to her.
“I’m sure you’ll get the chance to find somebody someday. Anybody would be really lucky to have you in his life,” he had said. Those words filled Twilight with hope, and the more she hoped the bigger her smile grew. However, she was so lost in her thoughts that she had not been watching where she was going and consequently bumped into somepony.
“Oh my goodness, I’m so sorry. I—,” Twilight trailed off when she saw who she had bumped into. The pony was a pegasus stallion with a yellow orange coat, blue eyes, and a blue mane and tail. The gold armor he wore indicated that he was a member of the Pegasus Guard. Twilight had bumped right into Flash Sentry’s pony counterpart.
Now, Twilight had met this Flash a few times before. The first time she had met him was at her first Princess Summit at the Crystal Empire where he had been serving under her brother and sister-in-law. Even though she had spoken to him a few times mostly to apologize for bumping into him, the summit had kept her so busy that the two of them didn’t go any further than becoming casual acquaintances. Unfortunately, every other time she encountered him afterwards was the same way. Eventually, Twilight gave up hope that that the two of them can ever be anything more than friends. Heck, if she wasn’t the Princess of Friendship, she would have given up hope that the two of them could even be that.
“It’s no trouble at all, Your Highness,” pony Flash replied with a bow. “I know it was an accident.”
Twilight felt her face turn two shades redder. If her crush on him, which she definitely did not have, had ever gone away, it had returned full force. She smiled at him awkwardly as she breathed deeply through her clenched teeth.
“Twily!” a white unicorn stallion in purple armor with a blue mane and blue eyes greeted as he walked up from behind Flash. He was Twilight’s older brother Shining Armor. “You’re back.” He pulled her into a hug which she returned.
When the two of them parted, Twilight greeted back, “Shining Armor, I’m so glad to see you. You didn’t put off your responsibilities to your family and the Crystal Empire just to come see me, did you?”
“As much as I want to say yes, I’m afraid that I am here on business,” Shining Armor replied teasingly.
“Oh, what kind of business?”
“The kind that’s been long overdue,” Shining Armor replied with much less humor. “I don’t know if you’ve noticed, but the position of Captain of the Guard has been left unfilled since Cadance and I were put in charge of the Crystal Empire. Princess Celestia thought that with you getting promoted to ruling princess, now would be a good time to finally fill it.”
“And I’m guessing that Mr. Sentry is your recommendation for filling that position?” Twilight asked her brother.
Flash’s eyes widened when he heard Twilight say his name, but he otherwise kept his composure.
“Excuse me, Your Highness,” Flash interrupted addressing Twilight. “I don’t recall ever mentioning my name.”
“You didn’t,” Twilight replied with a friendly smile. “I remembered from when Cadance first told me back at the Princess Summit.”
“That was almost four years ago; I can’t believe you actually remembered,” Flash exclaimed in surprise before he remembered his place and reined in his emotions, “uh, Your Highness.”
Twilight couldn’t help but giggle a bit at Mr. Sentry’s awkwardness. Even though she found him EXTREMELY attractive, she must remember that he was here on business, and the two of them had to keep their, for lack of a better word, acquaintanceship formal for now. That means no referring to him by his first name even mentally.
“Anyway,” Shining Armor resumed his and Twilight’s earlier conversation, “yes, I am, in fact, recommending Flash for my old job.”
“With all due respect, Prince Shining Armor,” Flash said to his superior, “as honored and flattered as I am by the recommendation, I don’t think I’m qualified.”
“Why don’t I take a look at your file and judge that for myself?” Twilight said to Flash, the kind, friendly smile still on her face. She turned to her brother and teasingly asked, “You did bring Mr. Sentry’s file with you, right, Shiny?”
“You know what? I did,” Shining Armor retorted with a roll of his eyes as he levitated a file folder out from the saddlebags under his armor. “I know how you are when it comes to paperwork and files.”
Twilight took the folder in her magic and opened it to read the papers inside.
“It says here that you were promoted after the most recent Crystal Faire,” Twilight read out loud, “for going above and beyond the call of duty.”
“With all due respect to whoever wrote that in my file, he or she gives me far too much credit,” Flash explained. “I was just doing my duty. I’m sure any other guard would have done the same thing in my place.”
“Maybe another guard would have done what you did, but you actually did do what you did,” Shining Armor countered. “That counts for something.”
“It also says here that you were injured in the line of duty,” Twilight continued to read.
“It was just a broken muzzle,” Flash replied. “I was fine after a few weeks in a cast.”
“You had to be put on a liquid diet until the cast was ready to come off,” Shining Armor added, “and I don’t recall hearing you complain once. I’ve seen stallions whine and gripe while recovering from less severe injuries.”
“What was there to complain about? I’m a guard. It’s an occupational hazard,” Flash deadpanned.
“I can see why you recommend him, BBBFF,” Twilight giggled. “He’s just like how you were when you were in the Guard.”
Flash could feel his face heating up at Twilight’s words.
“Why, Princess, I-I’m flattered,” he stuttered in response causing Twilight to giggle some more.
Twilight composed herself and asked in the most professional tone she could muster, “Mr. Sentry, the incident that led to your promotion sounds like quite the story. I would love to know more about it in your own words.”
“Thank you for your interest, Princess Twilight, but I’m afraid there isn’t much of a story to tell,” Flash recounted. “A group of Faire attendees just had a little too much to drink and got a little rowdy. One of them ended up throwing a rather heavy tankard at Princess Cadance and Princess Flurry Heart’s direction, and I intercepted it.”
“Yeah, with his face,” Shining Armor added with laugh, “and after this punk kid made sure to get my wife and daughter to safety, instead of waiting to get medical attention like a sensible pony, he goes back into the chaos to help the other guards break up the fight.”
“And to that, I say any other guard would have done the same thing.”
“Yet you’re the one who got promoted instead of this hypothetical other guard who would have done the same thing but didn’t because he is hypothetical and therefore, could not have done what you did,” Twilight refuted jokingly.
Despite his best effort to remain formal and professional, Flash chuckled at Twilight’s declaration and quickly attempted to disguise his laughter with a few loud coughs. Shining Armor immediately saw through Flash’s fake coughs and rolled his eyes.
“Captain, I know we’re here on business, but you are allowed to laugh,” Shining reprimanded before giving Flash a good-humored strike across the shoulders. That strike caught Flash so off-guard that he coughed for real. The surprised look on Flash’s face elicited another giggle from Twilight which prompted another laugh from Flash.
Twilight blushed when she realized that she and Flash were laughing together and quickly turned her attention back to Flash’s file using the folder to hide her face. Half a second passed, and Twilight was still hiding her face behind the folder and not saying anything. The prolonged silence was making Flash quite nervous, and he contemplated breaking it.
“She hasn’t said anything in a while. Should I say something?” Flash thought to himself feeling the sweat soaking his mane and forehead under his helmet. “Maybe I shouldn’t. She’s probably still going over and thinking through my credentials. Besides, what am I even supposed to say? Well, I could always compliment her. Wait, no. That might be a bad idea. That might come off as butt-kiss-y. Oooh, but I kinda want to compliment her. She’s just so sweet and funny and charming in an adorably dorky way. Oh crud! I just called the ruling princess of Equestria and my current boss’s sister dorky in my head! Oh, Heaven have mercy on my soul, and please don’t let either Princess Twilight or Prince Shining have the ability to read minds!”
“It also says here that you consistently do more than is required of you,” Twilight finally broke the silence and lowered the folder from her face. “Care to explain, Captain Sentry?”
“Oh, I have a tendency to take on duties that other guards feel are either not part of their job description or are below their paygrade,” Flash explained, “like doing safety drills and demonstrations at the schools, volunteering for tour group duty, or looking after Princess Flurry Heart whenever both Princess Cadance and Prince Shining Armor are busy with meetings or just need some time off.”
“One time, Flurry lost her Whammy at the park, and Flash got her to stop crying while Cadance and I rushed off to look for it,” Shining Armor elaborated. “We thought we’d never get her to return Flash’s lion to him.”
“Lion?” Twilight asked raising an eyebrow in confusion.
“Toy lion,” Flash explained before turning to Shining Armor and saying, “With all due respect, sir, you didn’t need to return it to me. I haven’t played with it in years and wouldn’t have minded having Princess Flurry keep it.”
“Sounds like you’re quite fond of my niece,” Twilight said with a smile.
“Well, I do have a soft spot for children,” Flash replied sheepishly.
“By the way, Twilight,” Shining interrupted, “I know I’m the one recommending him for this job, but it’s okay if you turn him down. Flurry is pretty fond of him too, and if he gets this job, he’ll have to move here, and Flurry will miss him.”
“Would she be willing to accept my toy lion as a gift to remember me by?” Flash bantered causing him and Twilight to share another laugh.
“You also mentioned doing demonstrations at the schools, Captain,” Twilight recalled. “I remember the guards coming in to do that at the School for Gifted Unicorns when I was a filly. Half of them seemed as if they’d rather be doing anything else.”
“Quite a few guards also feel that way about tour group duty,” Shining Armor added, “which is why it’s pretty notable to not only find a guard who is willing to volunteer for those jobs but also put effort into doing them well.”
“Prince Shining, please,” exclaimed Flash, “you’re making me blush.”
Shining Armor gave Flash another swat across the shoulders causing all three ponies to share another laugh. Then, Twilight looked back at Flash’s file and raised an eyebrow at what she just read.
“‘Not easily distracted by cake’?” she read out loud questionably.
“Yeah, it’s a surprisingly common problem in the Guard,” Shining growled exasperatedly. “I swear, I can’t seem to go through a week without reprimanding some boot for sneaking off to kitchens when they’re SUPPOSED TO BE AT THEIR POST!”
Flash slowly backed away from his superior with his ears flat against his head. Twilight just simply nodded as she bit her lip disapprovingly.
“It’s quite common for ponies to have a massive sweet tooth,” Twilight noted. “I guess that combined with both the stress and tediousness of working in the Guard is enough to encourage most guards to shirk their duties for an extra helping of sugar.”
“Yes, well, I’ve had to reprimand almost every single guard under my command at least once for getting distracted by dessert,” Shining continued with an eye roll. “Sentry here just happens to be one of the few I haven’t reprimanded, which can mean one of two things.” He turned to Flash and added, “Either you actually stay focused on doing your job or you’ve found a way to shirk your duties without me catching you. Tell me, punk, what’s your secret?”
Flash chuckled as he replied, “Oh, I keep snacks in my saddlebag just in case I get hungry while I’m on duty. I know eating on the job is frowned upon by some of the older higher ups in the military, but it keeps the temptation to sneak off to the kitchen at bay.”
“Oh my gosh, Shining Armor used to do the same thing back when he was in the Guard,” Twilight giggled. “His snack of choice was baby carrots. What’s yours?”
“Apricot fruit leather.”
“The kind with real apricots or the kind that’s just sugar and apricot flavoring?”
“Of course, the kind with real apricots,” Flash replied with a chuckle. “The other kind is just candy pretending to be fruit, and candy is the worst possible thing to snack on when you need to be alert and satiated for long periods of time.”
There was absolutely nothing funny about what Flash had just said, but Twilight couldn’t help laughing at it all the same. She awkwardly bit her lip as she looked away from him and turned her attention back towards his file. If Twilight was honest with herself, she would admit to herself that she found Captain Sentry leagues more interesting than his file and that she was just using his file to distract herself from her growing attraction towards him. Unfortunately, the rules of professionalism required that she remain distracted, so she continued to push her feelings to the back of her mind and kept her focus on the file.
“Hold on. ‘Notable military lineage’? What in Equestria is that doing in here?” she exclaimed even more confused than she was about the statement on cake.
“What IS that doing there?” Flash agreed, turning to Shining Armor. “With all due respect, sir, I fail to see why that would be a qualification for a guard captain.”
“It’s not,” Shining Armor explained as a tired and exasperated scowl crossed his face. “It’s a pointless status symbol that quite a few of the higher ups, specifically the ones from noble families, and a lot of the civilian elite THINK is a qualification.”
“Is that why some of the guards seem to have a harder time making rank than others?” Flash asked, his face contorting in disgust.
“Let me put it this way,” Shining Armor continued. “I had to fight some of the higher ups tooth and nail to make a lot of promotions happen, and you’re going to need to do the same when you become Captain of the Guard.”
“I’m sorry. ‘When’ I become Captain of the Guard?” Flash repeated blinking twice. “Sir, don’t you mean ‘if’?”
“No, I mean ‘when,’” Shining Armor replied bluntly.
“You seem awfully confident that I’m going to be giving him the job, BBBFF,” Twilight pointed out sternly.
“Oh, please, I could tell that he won you over the moment he brushed off getting his muzzle put in a cast and put on a liquid diet as an ‘occupational hazard,’” Shining Armor scoffed.
“I also said that you were only recommending him because he was a lot like how you were.”
“And that’s how I know that he won you over.”
Twilight opened her mouth to retort but couldn’t find the appropriate words to refute her brother’s assertion.
“Sweet Celestia, she’s adorable,” Flash thought to himself as he smiled at her annoyed and incredulous expression before he realized what he was thinking. “Gah! Stop it, brain! Stop it! She could potentially be your new boss, and you’re NOT allowed to think she’s cute!”
Twilight looked from the file to Flash to the file and back again. She pressed her lips together in thought before she closed the folder and levitated it back to her brother.
“Captain Sentry,” she began when she finally spoke, “if you don’t mind, could you and my brother please join me for a walk? Meanwhile, you can tell me more about your ‘notable military lineage.’ It’s not a factor in my decision in any way, but I am curious about it.”
“Well,” Flash began as the three of them began to walk through the castle hallways, “my grandfather from my mother’s side is a retired field medic, and my aunt, my mother’s sister, is currently serving as a drill instructor at Fort Jackscolt.”
“Really? That’s interesting. Shining Armor and I have an uncle in the Guard. He’s currently all the way in Neighpon, but he was the one who inspired Shining Armor to join,” Twilight replied. “I’m guessing that your aunt and grandfather did the same for you.”
“Yes, yes they did, my grandfather especially.”
“He, his aunt, and his grandfather also descended from Commander Magnus,” Shining Armor added before turning to Flash with a smirk, “which you seem keen on leaving out entirely, Captain Sentry.”
“Didn’t want to look like I was bragging, Prince Armor.”
“Wait. Commander Magnus?” Twilight cried in surprise. “As in the Equestrian hero of legend Flash Magnus? Oh my gosh, have you and your family had a chance to meet him since he and the other Pillars got out of Limbo?”
“He actually spent last Hearth’s Warming with us,” Flash replied with a laugh. “I think my younger brother spent most of his visit just staring at him.”
“I imagine you did your own share of fancolting as well, Captain,” snickered Shining Armor.
“I will neither confirm nor deny that statement, Your Highness.”
She couldn’t tell if it was the utterly unamused look on Flash’s face or the pointed tone in his voice, but Twilight once again found herself laughing at something Flash had said. As the three of them continued to walk, Twilight made up her mind about something. When they reached the entrance to the throne room, she had them stop walking.
“Well, I’m afraid this is where we must part ways,” she said to her two companions. “I will need a day or two to consider your qualifications, but I will give you my answer as soon as possible.”
“Of course, Your Highness,” Flash replied with a bow.
“Oh, and Captain Sentry,” Twilight continued when he had risen, “regardless of whether I make you Captain of the Guard, I certainly hope that the two of us can become friends at least when we’re away from the public eye.”
“I,” Flash stuttered taken aback by Twilight’s suggestion. “If that is what you wish, Your Highness.”
“You can call me Twilight, Captain. If the two of us are going to be friends, we’re going to have to drop the formalities.”
“In that case, you can call me Flash unless you’re planning on legally changing my first name to Captain.”
Twilight burst out laughing causing Flash to laugh along with her.
“Oh, come on, it wasn’t that funny,” Flash thought to himself in confusion even as he continued to laugh, “so why am I laughing?”
Flash and Shining Armor began to walk away as Twilight entered the throne room. Once the two of them were a considerable distance away, Shining Armor smirked and nudged Flash with his elbow.
“What?” exclaimed Flash.
“You LIKE my sister, don’t you?” Shining insinuated as his smirk grew bigger. Flash’s eyes widened and his jaw dropped.
“Sir, who wouldn’t like Princess Twilight? She’s kind, clever, and easy to talk to,” Flash replied as he sweated bullets under his armor. “It’s no wonder she’s the Princess of Friendship.”
“Captain, you and I both know that’s not what I meant,” Shining Armor retorted with a stern glare.
“Sir, if you’re suggesting that I find your sister attractive, I wouldn’t dare,” Flash said much too quickly.
“Relax, you little punk. I’m okay with the idea of you and my sister potentially ending up in a relationship.”
“You are?” Flash stopped in his tracks as he raised an eyebrow in confusion.
“Tell me, Sentry. How long have you been serving under me and my wife?”
“Well, about four years, sir.”
“And don’t you think that’s plenty of time for me to get to know your character?” Shining asked rhetorically before continuing, “I know you’re not the kind of stallion to jump into something just because it feels right. I also know that you’re the kind of stallion I can trust with my baby sister’s wellbeing.”
“So, I have your permission to find her attractive?” Flash asked hesitantly.
“If you want to and she agrees, you have my permission to take her out on a date,” Shining replied. However, before Flash could even start to relax, he added, “Of course, I’m still your superior and her older brother, so if you do start a relationship with her and it ends up going south, well, let’s just say you might need to go on another liquid diet.”
Author's Note
So, what do you guys think of my first pony!FlashLight fanfic? I hope I got the chemistry between them right. Speaking of chemistry, I wish I had thought up something more creative for today's prompt, but I really needed to resolve that bit I put in about Princess Twilight still being single while human Flash and SciTwi are about to get married, and this story both took care of that bit and (hopefully) satisfied the day's prompt.
For those who care, I tried to portray the Guard as competently as I could, but between what we've seen of the Guard in canon and needing to make Flash look especially competent compared to the average guard for story purposes, I'm afraid the Guard's portrayal came out rather unflattering. Sorry about that. 
On that note, just in case anyone is confused over how I used the word "Captain" in this story, it refers to both a military rank and a job position. Let me explain it this way. Shining Armor is recommending Flash for the position of Captain of the Guard, making him in charge of all the guards responsible for protecting Canterlot Castle. Flash was recently promoted to the rank of captain, which is one of the qualifications required for becoming Captain of the Guard. Does that make sense?
Also, Captain Flash's personal life is a bit different from human Flash's. For starters, his grandfather is still alive, and his aunt is still working in the military. Unfortunately, his mother is also dead, and his dad also isn't part of his life (granted, the reason behind that is different). I like the idea of the two universes being divergent from each other, so I wanted to move away from making the two Flashes carbon copies of each other.