It was early morning, and Cassandra, the Seventh Element of Harmony and long-lost sister to the princess, was enjoying her typical breakfast; quinoa and pomegranate salad, with a cup of the fanciest tea from the far east (only available to those with special connections.) A knock came at her door, it was Applejack.
"Howdy Cassandra. Mah apples haven't been sellin' very well, and ah have no idea why, but ah'm goin' door ta door. Wanna buy some?"
"They're not selling because everypony's tired of eating apples" explained Cassandra, "We could pretend well enough to like your apple treats because they had sugar, and a pastry part, but the apple itself, everypony's fed up with it. It would behoove you to diversify your crops. Maybe plant some other fruits like..."
"Ah see what ah have to do" said Applejack, "Ah have to sell mah apples even more aggressively!" She took an apple and whipped it at Cassandra, but Cassandra deftly dodged.
"That'll be four bits." said Applejack
"No," said Cassandra.
*****
It was two weeks later, and Ponyville's public health was in a decline. It had already been on the precipice because not everypony watched their figure as diligently as Cassandra, but their increased distaste for apples had pushed them over the edge. Now they sought refuge from the monotony of apples in Sugarcube Corner and its baked goods.
This problem had the potential to spiral seriously out of control, and required immediate action from somepony brave enough to take up the mantle, somepony like Cassandra. The fastest way to communicate a message to a town was to get somepony they all admired to deliver it, somepony like Rainbow Dash. And for that, they would need somepony Rainbow Dash admired, namely Cassandra.
Fruit was the obvious choice over vegetables, its sweetness would serve as a small step down from pastries. To convince Rainbow Dash, Cassandra would need a fruit that seemed tough, hard, defiant, like it was scoffing at Rainbow Dash. She considered using a fruit with spikes on it, like a kiwano or durian, but quickly reconsidered - she didn't want Rainbow to hurt herself by accident, as she was wont to do with sharp objects. No, the fruit had to be tough sounding but give up easily under pressure, because beneath Rainbow's tough exterior was a pony that really hated losing.
"Oh hi Cassandra" said Dash, greeting the visitor at her door, "what are you doing here?"
"I brought you a treat" said Cassandra, pulling a peach out of her saddlebag, "it's a stone fruit. Only the toughest ponies in the world can eat it."
"Yeah, whatever" scoffed Rainbow Dash, "I'll stick to my two dozen cupcakes if it's all the same to you."
"Your loss" said Cassandra. She took a bite of the peach, less daintily than she usually would. A trail of juice ran down her muzzle to the base of her throat. "Mmm" she remarked, "you are really missing out, Rainbow Dash."
Rainbow gulped. Secretly she'd had always had a schoolgirl crush on Cassandra, and she suspected that Cassandra knew.
"So sweet" said Cassandra, taking another bite, and rolling it with her tongue. Again, she let the excess peach juice drip from the corners of her mouth.
This teasing was unbearable - she wanted to just lean in and lick the peach juice off of Cassandra's face. But that would be too forward, she thought nervously. Instead, she put on an air of indifference, "A-all right, I changed my mind, if it's that big of a deal then fine, give me the peach."
Cassandra handed it over, and Rainbow took a bite. It was surprisingly soft, for a fruit so tough on the outside, kind of like her. It wasn't as sweet as a cupcake, but had a richness that satisfied her like no pastry could. She savored the squishy insides.
"Interesting" remarked Cassandra, "you took a bite from the same place as me instead of the opposite side. Some ponies would call that an indirect kiss."
"Wha'ever" scoffed Dash, her mouth full of peach.
"Now Dash, it's not polite to talk with your mouth full" said Cassandra. She stole the peach back and took another bite of it.
"Hey!" said Dash, "you can't do that! Give it back."
"Make me." Rainbow took the challenge and tackled Cassandra. Without getting off of her, she grabbed the peach back and took the last bite, leaving just the pit.
"Rainbow" said Cassandra breathily, "you're getting juice all over your face." She took out her handkerchief and wiped Dash's face. As she was drawing her hoof away, Rainbow Dash stopped her. She leaned down to kiss Cassandra, but Cassandra held her hoof up. She picked up the peach pit, and offered it to Rainbow Dash. Dash looked confused for a moment, but quickly understood. She took the pit into her mouth and sucked on it, drawing the last of the juices from the peach's core. She could taste the remnants of Cassandra, intermingled with her own, and it made her happy. Cassandra reached up and stroked her ear, a sensitive spot that few knew about.
Dash's heart began to beat, and as the caressing continued, she opened her mouth and offered the pit to Cassandra. Cassandra nodded and smiled, pressing her lips against Rainbow's and taking the pit for herself. She moved her hooves to Rainbow's wings and brushed through her feathers. Rainbow shivered and pressed against Cassandra for warmth. Unable to control herself, she began to lick Cassandra's face, lapping up the delicious remnants of the peach's juice. She moved down to Cassandra's neck, and Cassandra moved up to her wingtips. Dash cried out, and collapsed onto Cassandra, nuzzling the side of her face. Cassandra eyed a practice dummy, and spat out the peach pit, hitting it right between the eyes.
*****
Rainbow agreed to spread the word about public health and proper nutrition, with special emphasis on peaches. Thanks to Cassandra's initiative, all the ponies in Ponyville ate healthier and greatly increased their life expectancies. All except for Applejack, who choked on a peach pit and died.