It was just another end of the day in the town of Ponyville. Ponies were all sleeping soundly in their houses, tired after a long day of working their respective duties and jobs, and for some just exhausted due to excess partying, causing chaos, and yelling. At this type of hour, it would seem that even the most overexcited and hyperactive pony would be asleep, following the daily routine of the entire town. The entire town, that is, except for the library, which was the only light gleaming in the darkness.

Twilight Sparkle was busily finishing up a mystery potion while Spike was taking a seven-hour bubble bath for the second time in two weeks. At first Twilight didn’t mind, but after finding out that Ponyville unlike Canterlot had water and electricity bills, she tried to stop him from doing so, to no avail.

It wasn't because she didn't have enough bits, she just didn’t want the cost of his baths affecting her…secret experiments down at the laboratory. Drinking down the potion in one gulp, she sighed and knocked on the bathroom door.

“Spike! Are you done yet! You do know that you’re affecting the effectiveness of my work!”

Inside the bathroom she heard an annoyed snort of fire.

“What, another one of your experiments?”

“Sure, like you aren’t “experimenting” yourself with those seven hours…” Twilight grumbled silently.

“What was that?”

“Nothing Spike, just finish up already!”

“Ok fine! Go do your work or something, sheesh.”

As Twilight walked back to her desk, she heard a faint whisper.

“Up it goes and down it slides, up it goes and down it…BARF. Oh…”

There was a long silence, followed by a second running of water, some wiping of towels, then a long breath of fire before Spike held his hand outside the door.

“Letter from the Princess, Twilight.”

“Um…Thanks Spike.”

Trotting back over to her desk, she examined and smelled the fresh parchment.

“Why is this parchment cleaner than usual? Whatever.”

Twilight rolled out the letter, and read it.

Dear Twilight Sparkle,
The spell contained on the last page of this book is Star Swirl the Bearded's secret unfinished masterpiece. He was never able to get it right, and thus abandoned it. I believe you are the only pony who can understand and rewrite it. Princess Celestia.

“Ooh! Oh wow, Star Swirl the Bearded unfinished spell! And she believes that I am the only pony who can solve it!”

“Lame…” Came a voice from the bathroom.

“Shut up Spike. Let’s see this spell!” Twilight looked to the bottom.

From one to another, another to one. A mark of one's destiny singled out alone, fulfilled.

“Wait…what is this?”

Twilight was utterly confused as she read the line of text again and again.

“It doesn’t rhyme or make any sense! Does Starswirl the Bearded even understand friendship? Or is this about friendship at all? Why would Celestia send me a spell that might not even be about friendship or make sense?”

“Because she’s a troll?” Came the voice from the bathroom again.

Ignoring Spike, she continued to ponder.

“Well, I suppose it wouldn’t hurt to say the spell…I guess.”

She looked back at the parchment.

“From one to another, another to one. A mark of one’s destiny singled out, fulfilled.”

As she said these words, an invisible wave swept over Ponyville, causing a array of lights to shine in every house and the Elements of Harmony, which seemed to be surrounded in a protective bubble.

What was weirder was that no light came from the top floor of the Cake shop, the upper floor of the boutique, in two windows of the farm, Fluttershy’s cottage, Rainbow Dash’s house, and the tree house itself. Apart from those six places, Ponyville for a second glowed in a magical light that surrounded the town. As quickly as it came, it was gone.

“Well, this spell’s a dud. I don’t see anything-major happening. God damn it Celestia…Well, Spike, good night. I’m going to bed."

“Good night Twilight.”

As Twilight started to snore, Spike continued to play with his rubber duck.

“Up it goes and down it slides, up it goes and down it …"

Spike stared into the duck as he realised the depth of Twilight's words.

"Celestia why!”

Author's Note

Fun Riddle:
Why was the upper floor of the boutique, two windows of the farm, and Rainbow Dash's entire house not affected by the spell?