Summer. It's a nice warm day on Sweet Apple Acres, and local farmer Applejack could be found tending to the apple orchards. The summer harvest was only a month away, so all the apples had to be ripe and ready for bucking by that time. During the orange pony's inspection, however, she was interrupted by a sound: a whimper from behind her. Looking back, she could see a little red bow poking out from a couple of bushes. Applejack smiled.

"Applebloom," AJ began, "I know ya'll are there. You can come out."

Her sister did come out of hiding, but she didn't seem quite right. She had both a nervous look and a deep blush on her face, her legs were shifting around uncomfortably, and her cock was throbbing a little too-

... What? I didn't mention the cocks yet? Whoopsie. Let me back up.

There is a world parallel to Equestria. This world is nearly identical to the original, save for three key changes. One, to compensate for the lack of stallions in the nation, many mares were born as hermaphrodites. Really well-endowed hermaphrodites. Don't ask how, nature wills it. Two, with this new addition of body parts, the average sexual drive in Equestria is much higher, so you can expect to see or hear the sights or sounds of ponies getting it on. Three, a hierarchy was unofficially established; those without stallionhoods are subservient to those with them. Now, with that in place, let's get back to our apple ponies.

Applebloom stood before her sister, cock throbbing underneath her. Poor filly was the first herm to be born this generation, and was still getting used to her setup.

"Applejack," the yellow filly whined, "it feels weird again..."

AJ couldn't help but feel terrible for her sister. She herself was born a straight-up mare, so she couldn't even begin to understand her sister's pain, but she felt sorry for her nonetheless. Approaching her Applejack gently hugged her sister.

"I know, sis... I know."

"Well... can't ya do somethin' to make it feel better? It just won't go down."

Applejack could feel her heart skip a beat. She wasn't sure if showing her sister the ropes, so to speak, would be the best thing at her age. "Look, Applebloom, I think ya'll should just lay down and get some rest. It'll feel better later."

The young pony broke from her sister's embrace, shaking her head. "I want it to feel better NOW! Please, Applejack, make it feel better! Please!"

AJ winced and brought her stetson hat down to cover her face. She wouldn't be able to back away now; a pony with a cock had just given her a command. The orange farmer would have to obey.

"Consarn it..." Applejack fixed her hat and sighed. "Alright, go and lay on your back."

The filly looked at her sister curiously before complying, and she was soon on her back, her endowment standing at a full foot long, with a hefty, almost plush-looking sac right below the base. Applejack stood still for a moment, in a slight daze from the sight of her sister's member. After a moment of admiration and a dribble of drool, AJ regained her composure and sat down in front of her sister.

"Okay," she began, "this might feel weird at first, but it'll feel better, I promise." And with that, Applejack leaned her head down and took her sister's cockhead into her mouth. The filly gasped and arched her back, suddenly overwhelmed by the sensations.

"A-applejack! What are y-ya doing!?"

AJ tuned her sister out. She didn't feel like explaining the whole thing; she much rather preferred just showing her. Sliding her head down, more and more of Applebloom's length went into her mouth. Her tongue danced around the gently throbbing shaft and caught the warm drops of precum that began to dribble from the tip. 

Meanwhile, Applebloom was squirming and moaning, trying her best to wrap her head around the situation. Why was AJ's mouth around her thingy? Why was she sucking and licking it like a popsicle? And the biggest question of all: why did it feel so good? Her pondering was cut short as a sudden building sensation became apparent to her.

"S-sis... s-something's happening... It feels like it's g-gonna blow up..."

The older mare's ear twitched in response. She knew her sister wouldn't last long like this, and she wanted it over and done with quickly anyway. AJ began to bob her head and focus solely on sucking her sister dry. The filly's moans grew gradually louder, and the dribbles of precum soon became a steady stream.

"Applejack... It's c-coming... It's g-gonna blow!"

With the warning given, Applejack dove down, taking the length to the base. Applebloom gasped and arched her back as she hit her first orgasm of her life. Her balls churned heavily, her shaft rippled slightly, and her cock began to spew its load. Jet after warm, gooey jet of semen shot straight into Applejack's throat, and she shivered as she felt the substance slide down and pool in her stomach. She also began to swallow down whatever built up in her mouth, as to try and not  make a mess all over her sister. 

A minute of cumming and gulping later, both mares' actions died out. Applebloom collapsed and panted in exhaustion. Her now flaccid member fell from her sister's mouth and laid against her belly. Applejack swallowed the last helping of cum in her mouth and sighed. She didn't expect such a big load, and felt that she would probably skip lunch that afternoon. But what mattered now was that she was able to help out her sister. She looked at the tired out filly and smiled, gently lifting her up on her back and laying her against a tree, in the shade. AJ laid next to Applebloom and kissed her forehead.

"Applejack... w-we... we gotta do this again sometime."

And that's how Applejack became her little sister's mare.