Growing to a point where Sunset was sure her spine would break if she dared stand up, her breasts seemed to have settled down as the ponies within finally found her cleavage comfortable. "Pinkie?" Sunset barely finished asking before she felt a fuzzy touch between her thighs. Looking past her huge breasts was impossible, but she felt the snout of a pony press further and then, "Pinkie…" Sunset moaned softly as Pinkie's tongue ran along her slit from its base to its top, even pausing to give her clitoral hood a little attention.
Pinkie was all her little clones nuzzling around and squirming in Sunset's expansive cleavage, and she was the larger pink pony between her lover's legs. She loved Sunset with an intensity that the real world failed to correctly convey. However, Pinkie Pie wasn't in the real world right now and neither was Sunset. Wrapping her forelegs around Sunset's thighs, Pinkie licked at the presented vulva again and again, paying extra attention to Sunset's inner labia—knowing they were particularly sensitive.
After a few more licks, and getting particularly snuggly between Sunset's breasts, Pinkie moved her mouth up and pursed her lips.
When Pinkie captured her clitoris, Sunset felt paralyzed by pleasure. She was in Pinkie Pie's own world. Sunset had no hope of fighting free of her lover's mind, and didn't want to. It felt like jolts of electric pleasure radiated through her, forced into her body by Pinkie's suckling at her most sensitive organ.
Sunset's first climax was no surprise. She was shoved into an ocean of pleasure and could do nothing but let it wash over her and drown her in bliss. What caused Sunset to finally cry out her lover's name at the top of her voice, however, was Pinkie licking deep into her body.
Ears perked up, Pinkie loved the sound of Sunset's voice as she screamed Pinkie's name. But she wanted more. She nuzzled and licked, but avoided Sunset's oversensitive clitoris for the moment. As much as Pinkie could twist reality in her own world, she knew that Sunset would still associate feelings and situations to particular results.
One of the Pinkies in Sunset's cleavage climbed free and walked up Sunset's neck and up onto her chin. Looking down—Sunset was frozen in bliss and staring up from her slumped posture—Pinkie booped Sunset on the nose. With a jump to the side, the tiny pony grew as she flopped on the couch beside Sunset's head.
Struggling to process what had just happened, Sunset saw a closeup view of Pinkie's nethers. She didn't need to think to return the pleasure she was receiving. Licking and nuzzling, she ate out one of her girlfriend while another at her out.
Not caring that it felt like an eternity of pleasure to her, Sunset trusted that Pinkie wouldn't hurt her, and was able to just give herself over to the wild fantasy. It felt like days to her, but her body didn't ache and she was never struck by hunger or thirst. Sunset ate pussy for a week before Pinkie finally let the fantasy end.
Pinkie caught Sunset in her arms and, with a strength she rarely showed, carried her lover to their shared bedroom. "Sunny, we've gotta work on your stamina."
"Blarble?" Sunset grinned at her complete lack of sense. She felt amazing, though her brain wasn't exactly firing on all cylinders.
Giggling, Pinkie was careful to set Sunset down so she wouldn't damage her wings. "Yes, Sunny. Blarble. Also bluurk and blip." She kissed Sunset's forehead and sat down on the side of the bed to wait for Sunset to recover.
The world slowly started to make sense again to Sunset Shimmer. Up became up, thinking became easier, and her love for Pinkie Pie swelled to new heights. "You're the best, Pinkie."
"Nope!" Pinkie Pie leaned down to kiss Sunset on the forehead again. "You are!"
Both broke into a long giggle that resulted in a lot more kisses and almost another ride to the Pinkieverse. When they were both done, Sunset tested her legs and found them working. "Come on, Pinkie, let's go talk to your twin."
"Marble?" Pinkie Pie asked.
Sunset giggled a little more before managing to kiss Pinkie's cheek to calm down. "I mean the pony version of you."
"Oooooohhhhhh! Well, let's go!"
It wasn't a long drive to their old high school, and almost took longer for them to find a convenient and unmetered parking space. Hand in hand, they walked a block and a half to reach the school again, and soon stood before the square stone base of the old statue.
Cupping her hands together before her mouth, Pinkie Pie focused on all the happy and silly things that had happened, and laughed. She laughed and snorted, giggled and chortled into her cupped hands and then finally closed them as if there was an animal inside.
Sunset stared at Pinkie's closed hands. There was a pull of magic from them—something big was inside and wanted out.
When Pinkie Pie finally pressed her contained laughter against the surface of the stone, she felt the portal open and her hands fall into it. "Come on, Sunny!"
Having long-since gotten used to Pinkie Pie's way of life, Sunset Shimmer just abandoned herself to the alternate reality that surrounded her girlfriend, reached out, and took Pinkie's offered hand. She wasn't exactly pulled into the portal, Sunset jumped forward a fraction behind Pinkie.
Each of the girls felt the effects of the portal in an exactly opposite manner. Pinkie Pie turned from the form she'd been born with into a pony, and Sunset Shimmer turned from a human into her native form—though Pinkie had experienced this several times already, and Sunset was more comfortable as a human than as a pony.
Both stumbled out of the mirror on the other side and immediately tried to stand up on their hind legs.
Pinkie was the first to drop down to all fours. She watched Sunset try to keep balancing before she reached out a hoof. "Ponies, remember?"
"Oh. Right." Sunset let herself fall to a quadrupedal stance and felt an old familiarity come over her. "Kinda weird. After all this time, I'm back, and it feels normal. Guess you can't take the pony out of—the pony." When Pinkie giggled at her badly conceived statement, Sunset stretched her nose out and kissed her.
All the times Sunset had been in Equestria, she'd never kissed anypony. Pony lips were a little more sensitive to some things than human ones, and the current expression of affection was one of them. Both mares melted into an embrace, and neither planned to come up for air for a good while. In the end it was the sound of someone just outside the door that had them both gasp, break apart, and slink to standing behind where the door would open.
"Hello? Anypony in here?" Starlight Glimmer used her magic to illuminate the room, but when she couldn't see anything moving, made a soft expression of surprise. "I thought I heard something in here."
Only once the door was closed did Sunset let out a little giggle. "Why are we hiding?"
"Because if we tell Twilight about it, she'll ask us what we're doing, and I won't lie to her." Everything made perfect sense to Pinkie. "And I really enjoy coming here, and I know pony-me likes to spend time back home, and—"
Sunset had stuffed her hoof in Pinkie's mouth. She chuckled and kissed her girlfriend on the nose when she removed her hoof. "I get it, Pinkie. Easier to beg forgiveness than ask permission. Hold on—"
Sunset expected there to be a pomf sound. Magic teleportation always made that sound for ponies. Reaching a hoof up, she tried to brush at her horn but missed. "Well that's strange."
"What is, Sunny?" Pinkie asked.
"Well, I can't feel my horn."
"You don't have a horn."
"The wings—Okay, let's forget that for now. How do we get out of here?" Sunset didn't feel like she wanted to just forget not having magic anymore, but freaking out wasn't going to get them out of the basement of Twilight's castle. "How do you normally get out of there?"
"Open window. See?" Pinkie walked over to the castle wall and opened a window at ground level. "The castle always leaves it unlocked for me."
Sunset and Pinkie worked together to slip out the window. Everything in Equestria seemed just a little brighter to the both of them. The air was sharper, and it seemed like a lovely day was in progress.
Returning to the problem at hoof, Sunset reflected that the very idea that the castle did anything specifically for Pinkie didn't surprise her—this was Equestria and she was Pinkie. "Okay, well, let's find your other you. How close is—"
"Hi!" Pinkie Pie waved a hoof at Sunset Shimmer and Pinkie Pie. "Can I take it as read that Sunset knows that you and me keep swapping over and she came along because she wanted to see her old home and you're here as well because you wanted to ask me something super important that will make all of us happy?"
"Pretty much!" Human Pinkie said and lifted a hoof to clop it against her Equestrian counterpart's. "Would you like to come visit but we both stay there at the same time? It's just me and Sunset have started getting serious, and—"
"I got serious? Err, you got serious?"
"Yeah, the going-out kind."
"Ooooh! Not the actual serious kind?"
"Nope! The touchy-happy kind!"
Pony Pinkie's eyes widened and she looked between Sunset and Human Pinkie. "Congratulations you two! But I guess that means you're here to tell me we can't swap anymore because—Wait. You said I could come visit?"
"Yes," Human Pinkie and Sunset said a moment before they were caught up in a hug.
"We have a house with a spare room you can stay in and everything. Marble's living there, and Twilight, and Fluttershy, and Applejack, and maybe even Rarity and her girlfriend!" Human Pinkie hugged her double (and Sunset) just as tight as she was being hugged.
"So," Sunset Shimmer said, "Do you want to come visit for a while?"
After traveling over half of Ponyville, avoiding Twilight on the three occasions they saw her, Sunset, Pinkie, and Pinkie slipped back into the castle (through the open window) and back through the portal. It was only when she was back as a human that Sunset realized there was going to be a little more trouble with their plan.
Looking at both the Pinkies, Sunset was struck by the realization that not only couldn't she tell them apart (they'd wound up in identical dresses), but she felt physical attraction to both. No! Bad libido! Sunset told herself. "Maybe we need to get you both name tags."
"There's an easy way to tell us apart, Sunny," Human Pinkie said, "Only one of us will kiss you like this." With that, Pinkie reached out and pulled Sunset to her, pressing their lips, chests, and hips together in a kiss that had Sunset melting against her.
When the two finally broke apart, Human Pinkie looked between them with a sense of wonder, but eventually decided that a joke would be the best way out of any potential awkwardness. "Is that a challenge?"
"No!"
"Yes!"
Human Pinkie and Sunset looked at each other with challenging expressions, then both broke into giggles.
Pony Pinkie was left out of the argument, but she liked the change in Sunset. In her time spent as a human, she'd seen Sunset beaten down by her past, and she was very happy to see that her other self could make Sunset laugh so much.
"Pinkie, I just don't know you—That's not right, is it? I do know you. You've been here for some of my darker times, I bet. We've just got a bond that—" Sunset stopped talking and took a deep breath. "I can't think of a good reason not to at least try a kiss."
"Uh, Sunset?" Human Pinkie asked.
"What's up?"
"Well, when we went into the portal, we weren't ponied up, we just had our little pony ears and you had the little wings, but now I have a tail, and you have a tail. Plus, I'm pretty sure we only had the full mane when we ponied up before."
"You both look like pony girls! That's awesome! When does it wear off?" Pony Pinkie asked.
"It, uh, doesn't. We had a thing happen, and magic seems to be getting stronger in us, and the stronger it gets, the more we change." Sunset shrugged her shoulder, then rolled her shoulders. "These wings are heavier. They're going to make sitting down a little more difficult."
Pony Pinkie tilted her head then shrugged her own shoulders. "They look cute, kinda like the ones you had in Equestria. I thought Twilight said you were a unicorn?"
"Funny story there, too. Let's head home and talk about all this in private. Also, I want to freak the girls out a bit." Sunset reached one of her arms out to Pinkie, then the other out to Pinkie, and aimed them back in the direction of Pinkie's car.