My Little Diseases

Celestia storms into the castle, almost causing the door to fly off of its hinges as she makes her way inside. She looks around the castle frantically for Twilight, Pinkie Pie and her sister, Luna.
“TWILIGHT SPARKLE! MAKE YOURSELF KNOWN THIS INSTANT!”
Celestia yells into the castle. Her voice bellowing off of the walls and resonating down the hallways.

Twilight slowly exits the basement, looking at Celestia, her bloodshot eyes were wide, her mane was matted and frantic. Her wings were spread wide open, showing kinked feathers and a couple of bald spots along the wing’s structure.
Her uniform was now missing its sleeves, showing the scars along the backs of her front legs, and her grey-purple fur gave a soft sheen in the dim lighting of the castle.

“So…”
Twilight began, her tone cold, and heavy.
“You show up for your sister. But you don't show up, for your student?” She asks, her eyes locked on the larger alicorn, getting into an almost defensive stance.

Celestia did not acknowledge the question, instead keeping her eyes locked on her former student. The 2 alicorns began circling each other as they continued to speak, waiting for each other to make the first move.

“I must say Celestia, you’ve been rather distant ever since I became an alicorn.” Twilight began again.
“Ever since you gave me a pair of wings, you’ve been lending all the fights to me, you’re much stronger than I am, and you know it. I have a lot of magic to learn before I can even be considered equivalent to you. Yet you still send me to do all the work for you. As if you didnt want to actually do your job anymore.”

As Twilight says all of this, Celestia’s body is tense, as if seeing Twilight in this state has shaken her completely, and she was trying to keep her composure.
Soon the 2 alicorns stop moving, with Celestia’s back to the entrance of the basement, and Twilight facing away from the exit to the castle.

“Twilight you need to understand that I gave you the power of royalty to give you a better chance at keeping Equestria safe. You have more power than you ever could if you had remained a unicorn.”
Celestia tried to explain, her tone was calm and collected, but as she continued to speak, her irritation and upset became more apparent.
“But now I see that making you an alicorn was a mistake. I'm very disappointed in the paths and choices you have made for yourself. Your friends are dead, you’ve kidnapped my sister and you’ve lured me here… to brag?”

Celestia responded, her ears folding back and her eyes going glossy, her concern for her sister growing stronger with the longer she looked at the deranged scientist in front of her.

Twilight spoke up with a smirk.
“Well, I agree that subjects 1 through 4 were unfortunately lost while trying to make this town safe from illness. But it hasn't been in vain. With our losses we have learned how to finalise our vaccinations through testing tissue samples from our passed away subjects. They’ve been distributed throughout ponyville, and hopefully if other kingdoms and cities say yes, then we can distribute them there too.”
Twilight explained, using her magic to summon a small book that she’s been using to keep note of all of her work. Showing one of the pages to the Princess.
It was the cure for ‘flightless bird syndrome’, the infection that Fluttershy had.

It read that the vaccine was finalised about a month after Fluttershy, or as stated, subject 1, had passed. And that the infection was treatable if it hadn't gone beyond its third stage.
Once Celestia was done reading, Twilight made the book teleport back into the lab in the basement.
“But of course.. We need a few more subjects to make more vaccinations. I mean, the 4 we have made work, yes, but we need more in order to protect the town from illnesses that could come into fruition in the future.”

Twilight finished explaining what’s been going on, her grin returning to her face, but Celestia wasn't impressed, and she spoke up again.

“Making you royalty was a mistake… You should have never been given such a title.”
Celestia scowled, snapping her words at Twilight, but she never broke composure, the smaller alicorn simply stood there, her eyes twitching as she listened to Celestia’s words.

“Too Late.” Twilight simply responded.
Before Pinkie Pie suddenly covered Celestia’s eyes from behind. Catching her off guard.
The sun princess reared upon her back legs, her wings spreading open and her head shaking from side to side violently, trying her best to shake her off.

As Celestia was distracted, Twilight rushed forward, her footsteps causing Celestia to back up a bit as she continued to try and shake Pinkie Pie off of her head. Once Twilight was close enough, she headbutted Celestia just below her chest piece, knocking the air out of the alicorn, and causing her to stumble backward.

After a moment, Celestia managed to shake Pinkie Pie off, and she caught a glimpse of Twilight running out of the castle’s door, spread her wings and take to the skies.
Celestia quickly followed suit, spreading her wings as she ran after Twilight, taking flight the moment she was outside.
The sky was filled with exploins of yellow and black, as many many magical beans were shot toward each other, given Twilight’s size, she was a smaller target, making her more difficult to hit, while Twilight was able to get a few hits on Celestia, striking her back legs, as well as the back of her neck.

As Celestia saw Twilight flying toward her. But as Twilight drew near, Celestia didn't see a mad scientist. She saw her student, smiling wide, determined to complete another mission. Her fur was normal coloured, she wasn't infected with the Unseen Blight.
Seeing that image of Twilight flash before her eyes, caused Celestia to hesitate, which gave Twilight an opening.

The purple alicorn gave a determined scream, as both of her front hooves slammed into Celestia’s chest. The 2 of them began falling rapidly toward the ground, Celestia’s back facing the ground. As Celestia tried to orient herself to take flight again, Twilight prevented her from doing so, by using her teeth to hold one of Celestia’s wings still.

Soon the 2 of them slammed into the ground, leaving a fairly large crater behind, Celestia’s back hit the ground first, knocking all of the wind out of her, and causing the sun princess to cough up some blood in the process.
Celestia laid there, weak and wheezing as she tried to get the air back into her lungs.

Pinkie Pie slowly exited the castle, holding the bat. Twilight smiled wide to her love, nodding slowly, before Pinkie jumped up and slammed the bat into Celestia’s wing, a large crack echoed through the sky, followed by Celestia’s cries in agony, and then another crack.
Pinkie Pie chuckled softly as she gave the bat to Twilight, who walked toward Celestia’s head, using her magic to lift her head up by her mane.

“What do you think Pinkie?”
Twilight asked.
“Do you think she’ll make a good test subject for our next vaccination?”

Pinkie Pie gave a chuckle, before nodding in response. The 2 mares slowly giggled, which turned into laughter, which turned into terrifying cackles, as Twilight lifted the bat, swung down, and snapped Celestia’s horn in 2.