She has insisted on visiting the sick ponies.
"Stablehaven - It is on the very edge of our country, Your Grace." Glean, the head of the Royal Guards, had told her, as Luna had pulled down book after book with her magic, in an effort to keep busy.
"I can't tell you if that's a good thing or a bad thing - Good, so perhaps this disease will either not spread, or do so slowly. Bad...because, as you say, it is on the very edge of Equestria. What prompted them to settle there?"
Glean read the scrawled notes in the margin of the map. "Their settlers had crossed through the dangerous desert country - only a woody marsh separates Equestria from the Great Sands. They were perhaps too tired to consider going further when they found our country, settled for the night, and have simply never bothered to leave."
"I see." Celestia dipped her head, eyes clothed in thought, for a moment. She emerged and opened her eyes. "They need to know their Princess cares. I must also see how serious this is."
Luna looked up from the tome she was reading, dropping the book. "You? Why not me? I care, too! Don't you think they should know I care?"
Celestia blinked slowly, once. "Do you really think that you could make the trip?"
"...Even with the maps, I could not find my way. They are outdated, and this...Stablehaven was not around a thousand years ago." Like a chastised child, she picked up her book and placed it in front of her face, walking towards the shelf of books. "Only...do come back, Tia." She said, not looking at them.
Celestia smiled. "Bless you, Luna. I will."
She went alone, launching off of the balcony of her quarters and heading south. The only city visible was Cloudsdale, which was soon behind Celestia. Several hours of continuous flying later, the tall clocktower of Stablehaven came into view. The princess landed several feet away from the city on the path, lest her shadow frighten the citizens.
Stepping forward cautiously into the town, she looked from left to right. "Hello?" She said quietly. "I'm here to see the sick. I may be able to help them."
No voices came in reply. The low, gray stables were silent, as were the nearby shops. Closing her eyes, she conducted a spell that allowed her to locate anypony nearby - to her surprise, she found two cowering in a stable two houses down on her left, and approached quietly.
The door was jammed, but a well - placed hoof burst through it, revealing a splintered table behind the ruined door. "I'm sorry," Celestia said kindly, "But I don't think anyone heard me!"
Intuition buzzed in her mind. "What is going on?"
Two ponies, an earth and a pegasi, were huddling together in a corner. One of them looked up. "Our town - what's the matter with it?" She whimpered. "First, they were simply shaken with chills...then..." She buried her head in the chest of the other mare, who continued.
"...These great scabs...all over their bodies. Their eyes went white - next thing we know, they're snarling and attacking each other!"
"...And then?" Whispered the princess.
Suddenly, there was a great roar. Celestia turned around quickly as something bit her tail. There stood a unicorn, eyes milky white, shimmering strands of green and pink caught in his mouth. He roared again and charged his princess.
Not wanting to harm him, she pushed him away with her hoof, although with far more force than she intended, launching him into the building across the road. Stones crashed down around him. "Oh no!" Said the second mare. "They're coming!"
"Who? Who is coming?'
The reply was a mournful whisper. "The townsponies...it's all over..."
A few pegasi floated jerkily from the sky, mouths agape. Earth ponies with blood-filled scabs trotted toward the home, quickening their pace as they saw Celestia.
"What is the matter with them?" She wondered, pushing them back with a gentle pulse of magic.
The first mare was beyond consoling. "There - used - to be more!" She choked out "But - they - they ate them."
Celestia didn't want to hurt her subjects, regardless of their mental and physical state - but she had to somehow protect the two remaining citizens.
Her glance back at the pair sealed her fate.
Princess Celestia was quickly set upon by the three pegasi, flat teeth tearing at her mane and coat. Before she could retaliate, the Earth Ponies pushed her down with their hooves; The force of all of them brought down the Ruler of Equestria and began to bite at her body.
The last thing she saw before the Princess died was the two ponies screaming and trying to climb out of the window.
The last thing she thought was Luna...