The first one: imprisoned in stone for eons for following his nature, fully aware of his surroundings.
The second one: trapped on the moon for a millennium, completely alone but for the evil being her mind created, unable to free herself from either one.
The third: forced to banish her very sister, control the skies, and solve everyone's problems for as long as she reigns.

Why is it only one of these is considered insane? Let's take a look at the inner workings of their mind during their low points, shall we?

Periodically, the Princess leaves to Tartarus to rest undisturbed, as suggested by her stress counselor.

After falling asleep and having her egg timer wake her up from her extended lunch in the fiery landscape, she flies back out only to discover a voice.

The voice eludes her until she becomes concerned. Once It was found, she decides to contact Twilight for some friendly help.

If there was one thing Torn Note wanted to be, it was the best. Popularity, status, genius, she had it all. However, her ambitions to be the best destroyed her relationships with her friends— and perhaps even the world itself. And even still, she finds herself in the same wood, surrounded by the demonic creatures she unknowingly created.

Will she free herself from this time loop of demons and pain? Or will she have to face the music and fall to the wheel of insanity?

Discord has been asked ,by his friends, to help prepare for the up coming Summer Sun Celebration. But what happens when a fiendish plan is set into action and when Discord starts to feel odd new feeling for his closet friend.
____
(Fluttercord ship)

The Changeling war has been going on for just a few months now, and it has led up to this one point. One pony and One Changeling staring each other down. In front of them are two boxes, capable of wiping out both sides of the enemy, only there's a twist. No one knows what button does what.

Who can possible stop them from destroying each other and the lives of so many more?

Heavily based off of the Doctor's Speech in Doctor Who: https://www.youtube.com/watch?v=BJP9o4BEziI

Trixie keeps bragging about how she can speak Spanish but she never speaks a single word of it. Her bragging starts to grate on Spike as he's the one who has to listen to it all day. There's a ponyville talent show tonight and with a little help from his friendly neighborhood chaos bringer Discord, He makes a plan to make Trixie either put up or shut up. It goes about as well as you'd expect.

When Nova finds herself in a place she thinks she knows, without memories of her past, how she got here, and even missing some vocabulary, she is understandably confused. When a creature that she knows, despite her memory loss, is not normal claims she's brought hell unto Equestria, she's even more confused. With his help though, she'll get to see how everything led up to this, what happened to her, and why she looks the way she does.

One thing is for sure: something is very wrong, and somepony needs to fix it. Not the Elements of Harmony though.

As of now, possibly permanently cancelled, but not deleted because I may redo it entirely.

In Ponyville Twilight Sparkle summons the black city. The Agents of the Throne now must forge all their resources to stop the impending Apocalypse. In the deep jungles of the Amarezon a necromancer rises. Secrets will now be revealed that will test the will and power of friendship.

On the day Twilight, Applejack and Rainbow Dash are to give self-defence lectures to Ponyville’s earth ponies, unicorns and pegasi, Discord asks them to help him clean up a mess he’d left behind before he’d been turned to stone by the Royal Pony Sisters. This leaves Rarity, Pinkie Pie and Fluttershy to try and give defence lessons in place of the smartest, strongest and fastest members of Ponyville’s Royal Taskforce…

It's almost time....the contract has just one stipulation left. Just...one. After that...well Discord gets to make good on the promise he made to Fluttershy all those years ago,he promised her she would live on through more than just memory,but she made him sign a contract. It's so tempting to give that last part a tiny little push...but he knows better,the stipulations must happen naturally...but still,the wait has driven him sane.