After the Mane 6 had defeated Nightmare Moon, Pinkie threw her very first, 'Saved the World' party. Twilight got to stay in Ponyville and study friendship. Everything was wonderful.
Just as Twilight was rejoicing with her new found friends, Princess Celestia tapped her on the shoulder. " I would like the six of you to come with me" Celestia said. Her voice was kind, but firm.
They followed Celestia through Ponyville. Nopony said a word. Everypony but Twilight realized that she was leading them to the hospital. Why would she bring them there? They arrived, and Celestia led them inside. Further and further in. Finally, they reached the mental ward. There weren't many ponies in there, as there were better doctors in places like Canterlot or Manehatten. But there were a couple strays, kept close to their families.
"Why are we going in here" Fluttershy squeaked.
Celestia turned to face the six. "There was a pegasus found wandering the streets of Canterlot. She was rambling on, about being an ex-princess and being the seventh Element of Harmony, Trust. There is no seventh Element. I don't even know how she knows about the Elements! I was going to send her to a asylum in Canterlot, but.....I decided it would be best to have you help six help her. We could find no family connections. As a matter of fact, we couldn't find any record of this pony ever existing. We will continue to look, but for now....she will stay here. I only request that you help her. It is no requirement."
Twilight gulped. "We can look after her I suppose....but....what's her name..."
Celestia looked her in the eye. "She called herself Cassandra."
"S-she's not-t danger-rous-s, is she?" Fluttershy asked, fear in her voice.
"When and if you look after her, there will be doctors and security guards on watch. So far she has shown no sign of trying to hurt anypony. You may also request that she is put in extra restraints, when you visit her."
"May we see her now" Twilight asked uncertain.
"Of course. I will lead you to her room."
Celestia led them down the hall. She stopped outside of one door and nodded to the security guard. The guard took a key out of his pocket and unlocked the door.
The room was in no a way a padded, madpony's cell. It had blue walls and a matching carpet. Two wooden end tables with lamps sat on either side of a bed with a red bedspread. An empty bookshelf leaned against one wall. Against the other, was a dresser. If it wasn't for the emptiness, this room could have been considered cozy.
Under the covers of the bed, lay a pegasus mare, around the same age as the mane six. Her coat was a soft blue, her mane brown, long and slightly tangled. She had glittering, blue eyes. Her cutiemark was covered by the blankets.
Twilight approached, unsure what to say to the pony. The mare looked up at her, and smiled kindly.
"Hello" Twilight said nervously "So, I'm Twilight. The princess wanted me and my friends help you get better."
The mare just smiled vacantly.
"Well....We just saved the world from Nightmare moon and eternal night..." Twilight wanted the mare to say something, anything to break the tension.
"Well, that's just one of the perks of being a princess" Said the mare...Cassandra...kindly. "I stepped down from the throne because I was too powerful, but I still have all my powers. For I am the seventh Element of Harmony, Trust."
Twilight got up and told the Princess she was ready to leave. Just before she left the room, she turned her head and whispered to Cassandra "I will help you....somehow".