"What do you mean, 'Discord will be running the castle'?!" Twilight demands, upset that the Princess would choose the being of chaos over her own student.
"I'm sorry, but you've only been here for a short week. Discord has been here longer than you, so I find it will be better if somepony with more experience runs the castle while we're getting out rest." Celestia responds.
They're in Celestia's bedroom, the Princess lying in bed, while the furious Twilight debates over the fact that Discord could rule the land for a few days.
Discord laughs, having pleasure in Twilight's outrage. "Now, now, Twilight Sparkle, have no fear. It was you mares who helped me see who I can be." He pauses. "Oh wait. You didn't help."
"What about Cadence?" Twilight asks, ignoring Discord. "Or my brother? Please, anypony else!"
Discord gasps, faking to be insulted. "Do you not trust me, Ms. Sparkle? Why I am insulted!"
"Please!"
"Twilight, I'm sorry. Your brother and Cadence are in the Crystal Empire, so Discord will take over until we are healthy again." Princess Celestia says with a sigh, understanding her student's complaints. Even she's worried about leaving Discord in charge, even if he's been reformed.
Twilight groans as a response.
"Don't worry Princess, the castle is in good claws and paws!" Discord exclaims, then floats out of the room, Twilight following him with a grunt.
Discord walks down the white hall, Twilight right behind him. Discord glances over his shoulder at the Alicorn. "Why are you following me?" He asks, like he doesn't already know.
"To make sure you don't do anything stupid." Twilight replies gloomily.
Discord laughs, and snaps his claw fingers, causing the entire room to flash. Twilight blinks, and looks up angrily, expecting the worst. Though, surprisingly, she can't see anything different. Though something seems a little off... "Discord, what did you do?"
"Why, no crime has been committed! Just a simple flash, for fun!"
"Why are you being so over-dramatic?" Twilight asks, spotting how Discord isn't acting like his usual self.
"What do you mean, 'Over dramatic'?" Discord then falls on his knees, clutching his heart. "Why Twilight, why?" He wails, causing Twilight to frown. He laughs, puts her in a head-lock, and noogies her.
"Discord, I thought we were past trying to annoy each other." Twilight says, sighing. Discord releases her and teleports next to her.
"Ah, but what's the fun in that?" He asks, then snaps his claws, causing Twilight to grow a lion's mane around her neck. "Eh, doesn't look right," He snaps his claws again, and the mane turns a light purple. "Perfect."
Twilight's horn glows, and in a flash the lion's mane is gone. Discord floats around the corner, and Twilight follows, only to walk straight into a desk. "I swore it wasn't here before..." She mutters, and looks at the hallway. The red carpet has pink polka dots on it, with the walls have stripes. Oh, Rarity would murder whoever caused this.
If whoever caused this wasn't immortal.
"Discord!" She screams, and uses her magic to return the room to normal.
"What's wrong Twilight? Can't take a little change?" Discord asks mockingly, knowing Twilight can't do anything other than re-arrange everything he does.
"I just don't want this place turned into a funhouse before the Princesses are feeling better!" Twilight exclaims, getting annoyed with Discord's antics.
"Ugh, this place is so boring." Discord complains, wishing he could send avalanches of gum balls down the hallways. The walls are white, nothing on them, desks and other decorations are everywhere, and the rug is a plain red. He floats to the stairwell, where he goes down to the throne room. Twilight follows him, getting nervous at what he could do in there.
When she enters, Discord isn't there. Twilight groans, realizing he probably led her there so he could teleport to another room. She turns around to leave, when a furry paw is put on her head. She stops herself from screaming and twists her head to see what it is. Discord seems to have taken on the shape of a chandelier on the ceiling, and has his paw coming out from one of the candles. "Now that's just messed up," Twilight comments.
Discord turns back into himself, and floats down the the large throne the Princess normally sits on. Twilight sighs, and a guard walks in. At first he's shocked, but then gets suspicious. "What's going on here?" He asks, eyes furrowed.
Discord yawns, looking at the guard in the golden armour. "I have taken over Equestria once again." Discord replies, and evil grin on his face. Twilight attempts to intervene, but find her mouth sealed shut, probably from Discord's magic.
Discord snaps his claws, changing the guard's view. All the guard can see is chaos everywhere, and he runs out of the room screaming.
Once Twilight can move her mouth again, she scowls. "Was that really necessary?"
"What's wrong with messing around a bit? You're so uptight, Twilight Sparkle. You should really learn to let loose once in a while."
"I'm not uptight!" Twilight protests, but knows inside that she is. "Okay, maybe a little. But there's nothing wrong with it!"
"Argh, face it, you would die for the Princess."
"No! Only if it was for a reasonable cause! Like stopping you from destroying Equestria!"
"Why, I would never threaten Equestria in any way!" Discord objects, making an innocent looking face.
"That's a lie." Twilight says plainly. "Hey, remember that time, when you kind of took over Equestria, changed all my friends and I, then we kicked your flank and imprisoned you in stone?"
"Oh yes, then." Discord says, and an expression of sorrow crosses his face. He wipes it off quickly, though Twilight notices it.
"What's so sad about it? Evil is destined to fail. Though I guess you're not evil, more like, chaotic. It's in your nature, so I guess I can respect that." Twilight says. She searches her mind for any hints Discord could have laid about being turned to stone sad. Maybe it was painful, or it does something to him. Then it hits her.
Being turned to stone doesn't keep me from hearing every word Celestia says
"You were conscious."
The words hit Discord, and he inwardly slaps himself. He didn't want anyone to know. "Yes, but it wasn't that bad. Oh look!" He exclaims, changing the subject. He floats out of the throne room, Twilight following him with persistance. She wants to get down the the bottom of this.
"Discord, you were conscious in stone for a thousand years. How did you not go insane?"
Discord looks back, where Twilight stands still, a concerned look on her face. "Why, how do you know I didn't go insane? Maybe I did, maybe I didn't. I honestly don't even remember!" He exclaims, a hint of insanity in his voice.
"I have a memory spell-"
"But I don't want to remember those long years, now do I? How about you tell me something about you, that you haven't told anypony else?"
An answer immediately pops into her head, but she tries to swallow it down to come up with something else. However, Discord notices this. "Come on, Twilight. You know something about me no pony does, and now I can know something about you no pony else does."
"Actually, quite a few Ponies know about mine. Though I've chosen to forget about it, and no pony in Ponyville knows about mine. Unless you count Spike, but he's sworn into secrecy." She says, a small lump forming in her throat.
"Ah, but you can trust me. Is it a stallion you like, or I know! You failed a test once!" Discord exclaims, mocking her like she did with his failure.
"Not really..." Twilight says gloomily.
"Then tell me."
"But you have to promise not to tell, because I'm very ashamed of it."
"I was in the gardens with an embarrassing expression on my face for a thousand years. I promise not to tell anypony."
"Alright, here I go. When I was a filly, I was bullied. Like, a lot. I didn't have any friends, so I kind of kept it all in, and it started to become too much to bear. Though I didn't want to tell my parents, or my brother. I didn't even tell Celestia. So I wanted to kill myself and be done with it, so I found a spell that could do it painlessly. I used it, though whenever somepony uses it, it sends a message to Celestia automatically, saying who did it. When she found out it was her prized student... Well, she saved me, and told off the bullies. Life just became easier, and when I was on the verge of recovering, I was sent to Ponyville, where I met the other girls.
"So you can probably see why I cared about them so much. I was so afraid of losing them... Oh Celestia I'm going on a rant for no reason, sorry I must sound like a whiney little filly."
Discord is stunned at Twilight. He never expected the proud Alicorn to ever have something like that happen to her. "Well, I've had some pretty disgusting things said about me while I was in stone. Ew, what is that thing?! It's so disgusting! Get it out of my sight! Mommy, it's scaring me! Make it go away!" He says, mimicking voices.
"I-I'm sorry." Twilight says, and lies down on the floor. "Maybe I shouldn't have called you a goat that time-"
"It's okay, goat isn't very insulting. Hay, even my parents called me a goat!" He says, and starts laughing. "Now Twilight, how about you cut loose for once, and come have fun with some chaos among the castle?"
"I would like that." She says, and gets up.
"Frenemies?" Discord asks, extending his lion paw.
"Frenemies."