"My dearest Twilight,

"I am writing to confide in you a very deep worry; Luna has become withdrawn, irritable, and even tired. That is why night has been coming at erratic times. She is slipping in her duties, and I fear that something may be wrong with her.

"My sister has always been relatively weak when it comes to her health, which does not affect her power, please do not misunderstand... it just means that I worry over her more as a mother would than as a sister would. I am not certain what I may do for her, however... I truly hope this is simply a mood she is in and that it will pass quickly.

"I expect that my confiding something this deeply personal to you is very startling, but I feel that at the very least, I have told someone who knows Luna, and can be summoned in the event that she is needed to step in for my sister. Not that that will ever happen, Luna has managed to complete her duties, if not several minutes late or early..."

Princess Celestia gave a soft sigh as she took a pause from dictating the letter. The past several days had found her writing and rewriting this same letter, before discarding it. She hadn't had cause to be this worried about Luna in so long now, she was sure she was overreacting. Honestly, Luna was the picture of health, what need was there to alarm anyone?

She crumpled the scroll, setting down her quill and walking toward her chamber door. A walk around the castle gardens might settle her nerves, it often did.

However, a commotion from the hallway caused them to do just the opposite, and she flung open her doors as she sprinted down the hall, catching up to a small stampede of lavender-clad guards.

Luna's guards.

"What has happened?" she demanded, soaring over the group to the leader of the pack and running beside him. "What is the meaning of this?!"

"Something strange was heard from Princess Luna's chamber, your Highness."

They reached the doors to Princess Luna's rooms quickly, only to find them shut, the lock firmly in place.

"Luna!" Celestia called through the doors. "Luna, are you in there?"

"I can't open the door! Something's happened to the princess!" the voice of the younger sister's personal guard yelled back. "Please... it requires magic... please, Princess Luna isn't well!"

Celestia's horn lit, and the lock slid back, the guards and elder princess charging into the room. The pegasus guard was beside the dark princess's form, which lay on the floor, sprawled rather ungracefully.

"Luna!" the elder sister cried.

"What happened?!" the head guard barked at the dark pegasus. "What did you do to the princess?!"

"Nothing, sir! She said she felt lightheaded, and asked me to fetch her a drink, but before I could get to the door, she'd collapsed..."

"Did she say anything before asking for a drink?" Celestia asked.

"Only that her headaches were getting worse... she said something about 'the voice...' about wanting it to stop... Princess Celestia, I'm so sorry-"

The light princess squared her shoulders, and took a deep breath. "... It's alright. Someone fetch the royal doctor, and put Luna in bed. I have to contact someone."