“I’m the bad one!” Celestia said.

“No! [i]I[/i] am the bad one!” Luna insisted.

“But sis’, you [i]always[/i] play the bad one. I never get to—”

“What of it?” Luna asked, shrugging.

“I’m fed up playing the good pony. I want to change. Being always the good one…” Celestia hesitated, looked around to check if nopony else was listening and, finally: “…sucks.” she concluded in a whisper.

“Shush now!” Luna commanded. “Or I’ll strike you with my death ray!” Her horn pulsed with a soft glow. She was endeavoring to look serious, even a tad wicked.

They locked eyes. Celestia checked an urge to laugh. She broke the silent challenge, lowered her head. Suddenly she pounced on Luna. Both rolled on the floor until they bumped into the nearest wall. There was a loud “Ouch!”, and the moving knot of legs and manes undid with Luna standing atop a supine Celestia.

“See? Evil always wins, even when ambushed by an elder!” Luna trumpeted. “And now” – she emphasized each word dramatically – “I am going to crush you!”

“Mmmpf!” Celestia protested, gnashing her teeth as she wriggled to break free from her sister’s tight hold. Her horn lit up and Luna was repelled from the ground, flown away in mid-air while her sister stood up, panting. She grasped a necklace lying nearby on the ground, then brandished it. “These jewels will boost my magic and I’m going to be unbeatable!”

The floating Luna looked down disdainfully at the gewgaw. “That? Come on! It’s just chips of glass!” She chuckled.

“No, it’s not!” Celestia retorted. “They’re the most powerful jewels in this universe! I’ll call them the… …Elements of Harmony!”

“The what now?” Luna burst into laughter. “Such a crazy name! Where did you pick that up?” 

Celestia rolled her eyes, then walked to her sister. “Dad mentioned that name yesterday,” she whispered.

“Oh!” Luna made a gesture with her hoof and the spell that held her hovering dissipated. She landed next to her sister. “What can they be?”

“I have no—”

“DINNER’S READY!” A male voice called from behind the door.

“Uh oh!” Luna said. “We’d better get going!” Celestia nodded and they both walked out the room.

[hr]

“What were you playing?” Dad asked, looking in turn at the two sisters.

There was a short hush.

“Good colt, bad colt,” Celestia finally replied.

“And who was the bad colt this time?” Mom said.

“ME!” Luna blurted. Celestia mumbled something inaudible. 

Mom smiled. “Luna, you always play the bad guy, don’t you?”

“Sure! Good is so boring. When I’m a grown-up, I want to be bad,” she answered. “Not like her!” She pointed at her sister and hunched back over her plate.

Celestia caught a fleeting glimpse of her parents exchanging glances, but none of them spoke again and the dinner went on in silence.

[hr]

It was late. The children had gone to bed. Mom and Dad sat in their regal armchairs around the Sky Orb, whose glaring light illuminated and warmed the magnificent throne hall.

“She’s fascinated by evil,” Mom said. “It worries me, sometimes. I don’t want to repeat—”

“Don’t fret!” Dad cut in. He gazed afar, as if to lose himself in a daydream.

“What do you see?” Mom asked after a moment.

“We all make mistakes,” Dad replied, focusing back on her. “That’s the way we learn. We botched with our son, and we paid the price dearly. Luna is… different.”

“How do you mean, darling? I’m no soothsayer like you.”

“Remember we both wanted a sister for Celestia, but not a clone. Two of a kind, but not identical. I’m not sure what we let creep into her heart, but it came out darker than her sister’s. Hence her strong connection with the night. It might—” He paused. “It [i]will[/i] lead her to sinister places.”

“Will she—”

“Oh no! She also got her share of joy and light. If she stumbles, she will rise again, unlike him.”

“Do you still think it’s a good idea to give her co-rulership over that world?” Mom asked.

Dad pondered. “I think so,” he said at last. “I’m afraid it’s the only way for her to face and outgrow her fears and frustrations.”

“What about Celestia?”

“She will ride it out.” He turned to Mom with a smile playing on his lips, which she requited. 

And since they too were tired and had nothing to discuss anymore, they both went to sleep.