Reason #1 - Lazy
Peter’s mouth hung open, allowing drool to escape. Stretched across the bed with a hoof hanging over the edge, the stallion was lost in a deep slumber. Twilight’s brow twitched at the sight. They had plans, and Peter was sleeping in again. Her horn glowed, preparing to give the stallion a much needed wake up call, but Twilight hesitated, her gaze softening the longer she stared at Peter’s vulnerable body. He was always warm, his body heat quite contagious, and Twilight was addicted to it, a part of herself begging to join the stallion’s side.
Twilight realized what she was contemplating and used her magic to teleport Peter out of the bed, leaving the stallion to fall from several hoof-lengths in the air to the ground with an unceremonious smack.
Twilight rolled her eyes and trotted out of the room. ‘Such a lazy pony. Who sleeps past noon anyway?’
Reason #2 - Reckless
The bandages wrapped around his limbs and body were rather restricting, too much for one who reveled in free movement. Unfortunately, the fight had taken a toll on his entire physique. Peter groaned. It was times like this that he wished dragons were more reasonable, not having to be dealt with by force. Luckily, he was a fast healer and would only be confined in the hospital for a day. With his strength and agility, Peter could have easily walked out of the hospital, but he eased away from that notion, knowing the violet mare perched by the door would be perturbed should he try such a stunt.
Twilight shook her head, smiling sadly. “You look terrible.”
Peter sighed. It wasn’t like he could argue with her.
Reason #3 - Irritation
Peter knew how to irritate Twilight to no end with his laziness, reckless abandonment, self-sacrificing nature, and the thousands of stupid puns and references (half of which Twilight could never understand). Cadance always told Twilight that was the spark of their relationship, the flare that gave their love a unique light.
Twilight couldn’t understand what her sister-in-law meant to this day, adding to her irritation.
Reason #4 - Librarian
Beads of sweat fell from Peter’s forehead. “Please tell me we’re almost done.”
“No. We still have to find various materials for research,” Twilight said nonchalantly, keeping her violet gaze fixed on her book.
Peter moaned desolately. He struggled, adjusting his hoof to keep the staggeringly tall stack of books from falling. This was the price to pay for dating a heavy-duty librarian.
Reason #5 - Chemist
Experiments were prone to backfire on occasion. This was a fact. The new webbing formula was far from perfected, and there had been explosive results. Twilight stared wide-eyed at Peter. Webbing was stuck in his mane and his coat. Peter blinked, quivering.
Twilight shook her head. “I told you--”
Peter glared at the mare. “You so much as finish that sentence, and I’ll put so much webbing in your mane that you’ll have to shave it off!”
Reason #6 - Giddy
Then, it made sense. Peter held Twilight in his hooves, his hot breath brushing across her neck. He whispered sweet nothings into her ear, all while planting soft kisses against her cheek. She practically melted in his grasp, forgetting why she was upset with the stallion in the first place. This was quite normal, but Cadance’s words made sense now. Peter knew just how to get under Twilight’s fur. While he irritated her beyond measure, Peter knew how to make her smile just as often.
She would tolerate Peter’s idiocy as long as he remained like this.
Reason #7 - Dance
Twilight stood in the middle of the floor, flailing her hooves about. Everypony decided to celebrate Twilight’s alicorn transformation, but Peter stood flabbergasted, his sight refusing to leave his mare. She continued to move about, smiling as she attempted to dance. While he couldn’t dance either, Twilight’s attempts could be mistaken for ritual movements. Nopony or human moved like that. At all. However, Peter shrugged and joined Twilight by doing his own rendition of the robot, earning a pleased giggle from the mare.
Everypony on the dance floor eyed the couple, with expressions of shock, horror, and amazement. The night was perfect.
Reason #8 - Estrogen
Peter blankly stared at the ceiling. Twilight’s friends came over for a slumber party. Spike came up with an excuse to hide away in Canterlot Castle for the night, but Peter was left behind, forced to play along with the girls’ games of torture. As the only stallion in a group of mares, Peter was an easy target. Rarity loved to paint his hooves, Fluttershy enjoyed combing his mane, and Rainbow Dash reveled in taking pictures, wanting to remember Spider-Mane’s humiliation for all time. Applejack provided moral support through s'mores, but Pinkie Pie’s game of truth or dare added to Peter’s misery.
Peter deadpanned, “I’m going to die of estrogen poisoning one of these days…”
Twilight kicked him in the side, earning a sharp ‘ow!’ for her efforts. “Shut up.”
Reason #9 - Morning
Peter crawled from upstairs with a glare in his eyes. Seven in the morning was too early for anypony to walk around, let alone go somewhere. Twilight smiled at the sight, clapping her hooves together gleefully. It seemed her present worked, but before she could enjoy herself, Peter dropped the mangled remains of a clock in front of her, its gears and body smashed to pieces. Twilight lowered her head and sighed. At least she knew never to put a clock by their bedside in the future again.
At least not within punching distance...
Reason #10 - Twilight Velvet
The holidays were always special for the Sparkle household, and this year was no exception. Velvet’s son and daughter returned home, both with their special somepony. Their family was slowly expanding. Cadance was a wonderful mare, and Peter was a very sweet stallion who would surely marry her daughter sometime in the future. It hadn’t happened yet, but Velvet had full confidence the day would come...
However, something was on her mind, a matter that had been bothering her since her children found their lovers. Peter and Shining mindlessly argued with each other, the latter threatening the other to drop the last slice of cake should he value his life. Cadance laughed uproariously while Twilight groaned.
Velvet smiled, seeing now was as good a time to ask her question. “So, when can I expect grandchildren?”
Shining Armor and Peter, taken aback, accidently headbutted each other during their squabble, both stallions falling limply to the other side of the table. Twilight whined, her face flushing to a bright shade of pink, but Cadance’s expression turned bemused, the alicorn glaring at her husband. Velvet giggled mischievously. That was the exact reaction she desired.
Reason #11 - Complicated
Twilight furrowed her brow, staring at the moon in the sky. Love was not something that could be learned through a book or a synopsis. It was something that had to be learned through experience, but even then, Twilight had more questions than answers. She knew she was a mare not entirely in touch with her emotions, but she was learning, determined to know why Peter had affected her psyche so drastically.
She smiled. Cadance mentioned that love was a life-long journey. Even if it took her the rest of her natural life, Twilight looked forward to sharing that adventure with Peter.
Reason #12 - Simple
Winsome Falls was a haven for solitude. Peter and Twilight sat together, their gazes fixed on the waterfall at the center of the area. Twilight leaned her head against Peter’s shoulder, cooing softly. Peter pulled her closer and smiled as she nuzzled into his embrace. He let his lips linger on her forehead as he gazed into the misty evening waterfall. Sometimes the simplest pleasures were the best, especially if they were shared with somepony special.
Reason #13 - Overprotective
Peter was not a violent pony by any means, at least in terms of his personality. If anything, he was protective to a fault. Twilight never blamed him for that. After all, Peter lost his first love at the hands of a psychopath. However, that couldn’t excuse her knight’s rash action. Somepony, who had a bit too much to drink, made a move toward Twilight, and Peter retaliated with the utmost force, leaving the drunken pony with a broken limb and a concussion.
Twilight glared at Peter in a scolding manner. “Why did you do that?!”
Peter raised his hooves defensively. “I thought he had a knife!”
Twilight shook her head. “It’s a pen! He was asking for an autograph, you idiot!”
He stared at her, slackjawed. “Why is it blade-shaped and made of steel? I’m used to Bics and feather quills, not giant stabby pens!”
“He’s an earth pony!” she shot back. “It’s hard to mouth-write with a quill!”
Twilight moaned. Peter truly thought an assassin was after her, meaning he had every right-- both legal and personal-- to protect his princess. All Twilight could do was offer the drunkard a sincere apology and cover his medical cost. She loved Peter. His intentions were pure, and he was still recovering from Gwen Stacy’s death. She couldn’t fault him for reacting so strongly. It was just surprising. For somepony who made it a hobby to beat up crooks in his spare time, Peter was surprisingly nonviolent, and Twilight was grateful, having been reminded that her stallion pulled his punches for a reason.
Reason #14 - Thoughtful
Twilight came in quietly, shutting the door gently as to not aggravate Peter’s migraine. She carried the bowl carefully, making certain not to spill any of its contents on the marble floor.
Peter peeked out of the corner of his eye. “You’re still up, Twilight? It’s late.”
“I know, but you haven’t eaten all day. I made you some soup. Hopefully it’ll help your headache.”
His expression softened. He had never seen Twilight cook a meal during his entire stay in Equestria. He took the bowl into his hooves and took a sip without using a spoon. He grimaced. The broth was unappetizing, the seaweed was tough, and the mixture was watered down, leaving little to no taste. It was horrible. Soup was not hard to make, even for him. However, Peter managed to force the soup down with a few gulps and even managed a followup smile.
It’s the thought that counts.
Reason #15 - Klutz
Spider-Mane was a paragon of balance, an acrobat with no limitations. He had displayed this several times in Equestria, but it became evident throughout the world after his race with Spitfire. Peter was a unicorn who could even outmaneuver pegasi. One would think his love interest would have learned something, but Twilight was hopeless, a klutz at heart. She walked on the ice, her skates wobbling frantically beneath her. She slipped, falling flank first in the snow. Peter flipped over to her position. Twilight sighed. He could even ice-skate on his first try.
Peter helped her up, chuckling. “Klutz.”
She blushed. “Shut up.”
Peter laughed the moment she fell back in the snow. “Don’t worry. I think it’s cute.”
Despite having a sixth sense for danger, he still could not dodge the snowball that struck him between the eyes.
Reason #16 - Distraction
Poke.
One rule for everypony was to never bother Twilight while she was in the midst of her studies, but Peter found a way to be the one to defy the rule. It wasn’t often, but it was enough to leave an impression. At first, Twilight always bit, listening to what he had to say, even if it was pointless babble. Nowadays, she simply ignored him, knowing he would give up after a while, but today was different, as Peter poked Twilight for several minutes, begging to get her attention at least once. Her brow twitched madly. She could not take much more. Studying was important, but Peter didn’t seem to think so.
Poke.
That was the final straw. Twilight turned with her horn glowing brightly, preparing to teleport Peter somewhere in Equestria. It could have been Winsome Falls or the Everfree Forest. She didn’t care. She just wanted him gone. She would not let him distract her. Unfortunately, Peter was ready. The moment Twilight turned, his lips met hers with the greatest precision, drawing a speechless moment from the mare. His job done, Peter trotted out of the treebrary with a smug grin. Twilight shook the cobwebs from her mind and turned her attention back to her book, but an exasperated expression filled her eyes.
She lost her spot in her book. His distraction worked. Again. Twilight slammed her book shut and threw it behind her shoulder in defeat. One of these days, she’d send him to the moon.
Reason #17 - Applebloom
Applebloom peeked over the table. “Hey, Twilight. Can Ah ask you something?”
Twilight smiled. “Of course, Applebloom. What is it?”
The filly bit her lip. “Pete’s my big brother, and you’re his special somepony, right? Wouldn’t that mean you’re my sister?”
Glancing off to the side, Twilight paused before responding. “Not quite. You’ll become my sister if I get married to Peter.”
There was an awkward silence between the pair, but Applebloom grinned, as if satifisied with the answer. “Peter is always talking like he’s ready to marry you. So doesn’t that make us sisters already?”
Twilight’s entire face turned beet red. “No! I mean… yes! No! I mean it’s too soon! Just wait! We’ll get married later!” Her own hoof slammed over her mouth, concealing a peep. “No, we won’t! Just--!”
Rolling her eyes, Applebloom groaned. “Applejack was right. You two are practically married already.”
Needles to say, Applebloom was surprised to see Twilight slip from her chair, but the filly was pleased, evident by her smile. Twilight’s response was very similar to Peter’s.
Reason #18 - Possessive
She wasn’t jealous.
The entire world knew about her relationship with Peter, the amazing Spider-Mane, but there was a hint of doubt, something pulling at the back of her mind. Her stallion had admirers, hundreds of thousands of them. It wasn’t that she minded. After all, so many ponies admire Princess Celestia and nothing comes of it. Twilight snorted, pacing across the room in a huff. Some would fly into a fit having learned Spider-Mane had a special somepony. Twilight stopped in her tracks. Peter was hers.
The endearment was possessive, but she didn’t care. Peter was the only one who made her feel this way: wanted, loved, and cherished. It was selfish, no way for a princess to act. However, Peter cleared his throat, prompting the mare to turn sharply and face him. He extended his hoof, waiting patiently. Twilight accepted the gesture, and Peter pulled her close into a warm embrace, nuzzling his face into her neck. His warmth spread through her. Twilight shivered at the tingling sensation she grew to adore.
She tightened her grip around his neck. “You’re mine,” she whispered possessively, pressing her lips into his. She drank him in, cooing as his teeth nipped her lower lip slightly. He just marked her. Twilight pulled away much slower than she should have, but she maintained eye contact with the stallion, giggling lowly. “You’re only mine.”
She wasn’t jealous. Even if she was, it was fine. Peter echoed her sentiment.
Reason #19 - Chivalry
Peter smiled. “Allow me.”
The stallion lifted Twilight into his hooves bridal style, walking upright as he carried her through the courtyard. The ground was wet due to the heavy rains, and Twilight was wearing her favorite pink dress, prompting Peter to come to her rescue. After a brief journey, the couple reached the inside of the castle. Peter’s lower hooves were drenched as he gently placed the princess down, but he didn’t mind, evident by his cheeky grin.
Twilight shifted her gaze from the outside before directing it back to the stallion. “That was sweet of you, Peter, but you do know I could have teleported, right?” Peter shrugged, causing Twilight’s cheeks to glow. She leaned forward, giggling as she planted a kiss on the stallion’s cheek. “You’re the perfect knight.”
Reason #20 - Promise
Twilight wrapped her hooves around Peter’s neck. “I want you to make me a promise, Peter. Don’t you dare leave me behind. No matter what happens… we’ll see everything through together. Okay?”
Peter placed his hoof over the mare’s shoulder. “I’ll never leave you behind.”
A blush filled the cheeks of both ponies before their lips met for a passionate kiss. They remained as such, savoring each other’s taste. Twilight moaned inside of Peter’s mouth as his tongue explored the sanctions, touching the most sensitive areas with gentle precision. She melted into the act of affection, bending to her lover’s will, but they eventually parted, only due to their need for oxygen. Peter’s lips curled into a wide smile as Twilight’s face flushed immensely. He offered her his hoof, and with a soft nod she accepted the gesture, not taking her violet irises away from his hazel eyes.
Peter grinned. “No matter what happens…”
Twilight giggled. “...we’ll see everything through together.”
Reason #21 - Common
They were worlds apart, two individuals brought together by severe circumstances. Peter was an alien living among ponies, his body having changed due to the magical properties of the atmosphere. Twilight never looked at Peter as an outsider. In fact, she had more in common with Peter than she had with anypony in Equestria. Granted, they had a few differences, but considering where they stood now, it was easy to say Twilight found somepony who meshed well with her. Peter was an alien, but he was still the greatest pony Twilight ever met, at least in her eyes.
The reverse was true. Twilight accompanied Peter to his world. Their stay was temporary as they had business to take care of. Much like Peter did in Equestria, Twilight's body transformed to that of a human when she came to Earth. However, Peter never thought twice about the change. He had more in common with a sentient pony than he had with any woman on Earth. He smiled. As far as Peter was concerned, Twilight was a human disguised as a pony. It made sense, unless he was actually a pony disguised as a human. Peter no longer really cared about the details, and Twilight never paid them any attention from the start.
Whether they were ponies or humans, Twilight and Peter loved each other, and that was more important than anything else.