A green I originally wrote with Twilight as her r63 self Dusk Shine, but I reworked it so that he was Twilight again. Might post the other version sometime. Wrote this before Potion Nove from Pony Life was even a thing, I think.
 
>You are Twilight Sparkle.
>Boredom is all you have today.
>Nothing of note is occurring outside, nothing making you go on any adventures — there is nothing happening.
>Nothing at all.
>No monsters to battle, no conundrums or super-villains to banish, just the the clock slowly ticking away as you flip to the next page of your book, sitting in bed.
>It’s an interesting little thing you’ve been reading, actually.
>It’s about the chronicles of a pony, stranded in a town out in the old pony west, fighting to bring law to a lawless town.
>You particularly appreciate how knowledgeable the author is in how he made the protagonist a lawyer — an occupation for a character that you have seen only a select few authors write well.
>Law was complicated in Equestria, and the way the character was written proved that the writer did his research for this story.
>It was effort like that which made you always appreciate authors more, especially since many tend to just write something and hope to get lucky.
>You don’t like that.
>Then again, whatever floats a pony’s boat, right?

KNOCK! KNOCK! KNOCK!

>Three knocks hit your door. 
>A grumble escapes you.
"What is it Spike?" you holler. "I'm reading!"
>“Uh, Twilight? Somepony’s downstairs asking for a book…”
>You sigh.
>A librarian’s work is never done…
“One second, please,” you say, and save your spot in the book. 
>Page number 831, middle of the page during Chapter 32. 
>Got it.
>You rise from your bed and stretch before you the bedroom door.
>You yawn as you walk past Spike towards the stairway.
“Who is it and what book do they want?” you ask the little guy.
>He follows you as you both walk down the steps.
>“Oh, yeah, it's Pinkie Pie, but, uh, she seems kinda twitchy, though. Like, really twitchy. And I don't think it's her Pinkie sense this time...”
 
“Uh-huh. And she didn’t say what book she needed, did she?”
>“Nope.”
“Great. Wonderful. Just great.”
>You stop halfway down the steps to look at your dear assistant.
>“Alright, listen here, Spike; if she offers you any thing to drink, any food that looks good or that you might want to eat-- DON'T. It’s likely to have traces of some bootleg potion or something.”
>“Potion?” says Spike, his face askew.
“Yes, a /love/ potion. She’s been obsessed with the idea of Love. Crazy about it.”
>“Like Cadance?”
“Pfft, or Chrysalis,” you mutter, and continue descending to the first floor. “When Pinkie heard I did a potions course in Princess Celestia’s School for Gifted Unicorns, she practically begged me to teach her how to make a love potion.”
>Spike’s eyes widen.
>"Yikes."
“Yeah, exactly.”
>“But Twilight, I mean, you're not going to, right? Like, teach her how to make one?”
>You scoff at the thought.
“Ha! Are you kidding me? After what happened with the Want-It-Need-It spell and the incident with Big Macintosh and Cheerilee? Please, Spike. As if!”
>You walk down into the library’s main room.
>There you find Pinkie fiddling with her tail nervously.
>When her sapphire eyes land upon you, she sucks in a breath of air and smiles.
>“OMIGOSH! TWILIGHT!”
“Hey, Pinkie,” you say with a lackluster wave, "how’s it — ACKK!”
>Pinkie Pie wraps her forelegs around you in a tight hug.
>“Wow, Twilight, I was totally freaking out! I thought you guys were closed today for some reason and that I was showing up here when I wasn't supposed to even though I reeeaaaallly need your help bceauase I got this huge thing that I've been trying to do and I need your help cause you're the only pony who can help me in all of Ponyville aside from maybe Lovestruck, Redheart, and a whole bunch of other ponies not as super smart as you are,!!!”
>She chokes the life out of your lungs, crushes your ribs with her strength...
>You wonder how she hugs her grandparents without killing them likes this.
>Unless…
 
>Spike watches on, cringing in horror.
>Not even he’s ever seen her give a hug this bad, this urgent.
>Eventually, the stars align in your favor and Pinkie relinquishes you, dumping you the floor like a sack of potatoes.
"Oy...What do you want now, Pinkie? And it better not be what I think it is.” 
>Pinkie Pie just giggles, unaware of the pain she has caused you, of how the peace and tranquility of your day has been ruined by her abrupt visit.
>“Oh, c’mon! You know what I want, Twilight!”
>You rise from the floor with a groan, aching and whatnot.
“And you know I still won’t help you, right?”
>“Aaaaaw, pretty please? I’ll do anything for it! Really!”
>Spike can’t help but grin.
>“Anything, huh?” he says coyly. “Can you, say, get me a bowl of gems?”
>To his surprise, Pinkie Pie nods  faster than a bobble-head.
>“Sure can! I've got a whole stash saved for your birthday!”
>“Whoa, really!? Awesome!”
>You roll your eyes at Spike...albeit with a smirk.
“Sorry, little guy. Not gonna happen. We’ll find you some gems later if you're that desperate.”
>“But what about me?” asks Pinkie. “I need a love potion because I'm desperate.”
“No, you /want/ a Love Potion, not /need/,” you say to her sternly. “There’s a big difference between the two. You, unfortunately, don’t know seem to know it.”
>“Aw, but I really DO need it,” she says, wining like a filly. “It’s really, really important!”
“You want to do something to somepony,” you say flatly. “Don’t you?”
>“Yeah! Somepony cute, and smart, and nice, and sweet, and silly, and...”
>Groaning, you bring your hoof to your face.
>And another over her mouth.
>You know, to stop her from talking.
 
“Pinkie," you say, "love potions are dangerous! They’re difficult to make, they're difficult to use, and they’re not safe either! Now, if you would like to borrow a book, then I’d be happy to help, but if you’re going to keep bothering me about this, then please, Pinkie: Leave!”
>The pink mare hangs her head low with a sigh.
>“Oh, okay…”
>She sulks her way to the library door; you lead her to it just in case she has any surprises in store.
>But then, right as she steps her very first hoof outside of your home, she looks backs at you and smiles.
>It's a very soft, cheeky, coy kinda smile. 
>And her eyes hold on you for a while longer than you're used to.
>You tilt your head at her.
“What?" you ask. "Do I have something on my face?”
>Pinkie's smile settles into a smirk, and she begins closing the distance between the two of you.
>Then, as she bats her lashes, you find your noses aren't even an inch apart anymore, and her cheeks are rosey.
>“Aw, who am I kiddin’?" she says happily. "Love potions' are for saps anyway!”
>Then, her lips are hugging yours.
>Your eyes widen as she only deepens the smooch. 
>She even slides a little tongue in there as well.
>You think you’re paralyzed; all you can do is stand there, face on fire, feeling unsure what to do, what to think!
>It’s like your heart is beating out of shock, but the powerful beat invigorates you all the same...until you slowly feel yourself relax.
>But then, just as soon as the kiss had began, Pinkie ends it and slips away.
>“Mwuah! Call me, cutie!”
>She winks with a little giggle and a snort, then prances off into town before you. 
>Meanwhile, you’re as still as a statue.
>In fact, you wonder if you’ve met the same fate as Discord and blink just to see…
>And then maybe blink a few more times.
>You know, just to be sure.
 
>When it seems that, yes, this indeed is reality and not, as you were beginning to suspect, some weird dream, you slowly slink back inside library and close the door with a trembling hoof.
>Spike stares, gawking at you. 
>Fifteen seconds go by. 
>Neither of you make a sound, as if trapped in silence.
>Finally, Spike is the one to break it.

>“Uh, Twilight? Did she just— ?”
“Yep.”
>“So, uh, that means the love potion was for you then, right?”
“Uh-huh.”
>“And that means…?”
>You sigh.
“Well, Spike, she was going to do things to me,” you say shakily. “But with love.”
>Your eyes wander down to the floor.
“I don’t know if I feel touched or violated, to be frank with you.”
>“Well, I guess technically you could say both.”
“Not now, Spike!”
>Stupid sexy Pinkie Pie...
>...
>Did she really think you were sweet?
 
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I'm pretty pleased with this one. I think I did a good job on Twilight's dialogue and the way she and Spike sometimes interact, especially in the early seasons where the two are more sibling-like in behavior and display sarcasm. I also think I just did a good job with the scenario, making it cute and surprising. 
 
I had that one scene from 'The Sword in The Stone' in mind when I was writing this, the part of the movie where Merlin turns both he and Arthur into squirrels only for this cute girl squirrel to be so haplessly in love with Arthur, her energy and spunk and flirtatiousness just absolutely endearing, so much so it almost steals the rest of the movie. It really captures the whimsical highs one can feel when succumbing to love at first sight, how playful and coy that one person can be with you when he/she likes you. It's the innocence of love at its most playful. 
 
Thank you for reading this, and may you one day feel the same electric vitality of attraction to that one coy boy or gal.