The Spark.
Diamond Tiara asked her father to buy her a dress from the boutique because it is the finest fashion in town. And while the fashionista was working on her custom fit dress, Diamond Tiara was listening in on Rarity’s conversation with her friend Twilight Sparkle as she was telling her of the latest test results from Sweetie Belle’s last check up at the hospital.
“...and its a shame that she can’t even perform a basic levitation spell, mother.” Rarity said. “she’s much too old to not have such a basic grasp of magic, even I at that age was able to lift a lemon.” She said to Twilight as she is measuring and sewing a dress for Diamond Tiara.
“Huh... I might know of a disorder that could cause unicorns to be incapable of ever using magic.” Twilight replied as a small smirk formed unnoticed on Diamond Tiara’s face.
“Oh, really, that would be such a shame,” Rarity said, “some might think of her as some kind of freak.”
“Don’t say that, Sweetie is not a freak,” Twilight protested, “its not that uncommon for a unicorn to be unable to use magic.“
“I know, but just imagine how much of a freak she’d be,” Rarity continued as she waved a hoof to emphasis, “being the only unicorn in Ponyville unable to use even the simplest of magic spells.”
“Rarity, she will not be a freak,” Twilight repeated. “And besides, there was a time you couldn’t use magic ether.”
“Yes, but I was half her age, darling,” the fashionista said as she finished up the dress, and gave the bill to Rich who waited patiently in the other room.
On her way home with her father, Diamond Tiara could not stop thinking about the juicy dirt she gets to rub in Sweetie Belle’s face at school the next day.
The next morning came faster that Diamond Tiara expected. And she didn’t waste a second putting on her new dress and heading out the door for school, to meet up with her friend Silver Spoon. As soon as she was in her seat right next to Silver Spoon, she couldn’t stop fidgeting, while watching the clock and didn’t hear a single thing Miss Cheerilee said all day. She gave up waiting for reases and decides to write a note.
“Miss Tiara! Are you passing a note?” Miss Cheerilee called her out.
“What? No! Its a piece of tissue, I swear,” Diamond Tiara defended. Everypony in class could see the lie dripping through her teeth.
“I’m sorry, but you know the rules. Now come to the front of the class and read out loud what you wrote.” Miss Cheerilee demanded.
“Yes Miss Cheerilee,” Diamond Tiara obliged as she slowly trotted to the front of the class, with an expression of... not shame, but glee?
“Now, go ahead, and tell the whole class your little secret,” the teacher stated.
“Okay,” Diamond Tiara said as she cleared her throat, “Sweetie Belle is a freak of nature because she is a unicorn and can never ever use magic,” She read aloud then looked up to see the shocked faces of her peers, and to see the deeply cut scar in Sweetie’s eyes as he starts to cry.
“Useless blank flank unicorn!” Silver Spoon said taunting Sweetie Belle, whose coat faded to an even paler shade of white as the endless fountain of tears began.
Sweetie Belle could only nod in response as the fear and shame grew heavy on her shoulders. Her best friends trade glances at each other. The rest of today’s class was going to be a long one.
“Diamond Tiara! Why in Celestia’s name would you think to say something like that!” Miss Cheerilee scolded, “And Silver Spoon! This is not something anypony should ever laugh at! What if you had a disability and somepony made fun of you?”
Scootaloo’s left eye twitched to those words.
“But, Miss Cheerilee!” Diamond Tiara whined like a foal, “I didn’t do anything!”
“Wrong, you laughed as something made up just to hurt somepony’s feelings.” Cheerilee continued, “And this is really not something to laugh at.”
“But Miss Cheerilee, I didn’t make it up,” Diamond Tiara defended, “Rarity told me her self, Sweetie Belle is a freak!” This statement made the whole class grow dead silent.
This caught Cheerilee off guard for a moment, the thought of a sister saying such a thing about a sibling was an unsettling thought, however she quickly regained her composure and responded, “I don’t care if Celestia herself told you that she was, that word, you don’t go calling other ponies cruel names like that.”
“Sweetie Belle, is this true?” one of her best friends Applebloom whispered so quietly you could hear a feather drop, and with a level of worry in her eyes nether Scootaloo or Sweetie have ever seen.
“How can that be? Your sister loves you!” Scootaloo said, as school was let out early for the three so they could walk Sweetie Belle home as she is losing the will to walk, but the rest of class was told to stay so Cheerilee could lecture the class about bullying. After which Diamond Tiara and Silver Spoon were told to stay for their first day of detention.
