//EDIT: Changed the background. Added my version of the book illustration from 'Hearts and Hooves Day'. Now the background more interesting and allude to the AU backstory. //

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Sometimes, there's more to tales of the past

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It was the first time for Princess Celestia to not only have two personal students, but both of them become alicorns and princesses at the same time. The two ponies were Cosmic Prism and Potion Nova.
Both of them were powerful, but Potion Nova stood out. Her magic wasn't really stong and she wasn't really a good spell caster. The field she excelled in was creating potions, powerful ones that even succussed ones made by her peers.
She was proud of her creation and was praised for it by everypony. She believed every problem can be solved by a well crafted potion. Even love.

The two of them became friends with Prince Gallant, the ruler of a small kingdom.
One day Gallant, trusting Potion, told her his love for Cosmic, but how he didn't have the courage to tell her.
Potion was certain Cosmic loved the stallion back, she was just shy to admit it. This may become one of her greatest achievement, and she could help her friends out, this was her thoughts. She could create the first working love potion.

She worked day in and day out, and one day she succussed. Potion proudly presented the potion to Gallant, telling him this all he needs, so he and Cosmic could have eternal love. Potion was blinded by her ego and couldn't foresee what would yet to come.

Gallant and Cosmic did fall madly in love, but it was 'madly' in a literal sense of the word. They wouldn't take their eyes of one other, wouldn't care about their surroundings or any pony else. They didn't care if any harm came in their way.
Torn apart, they would lash out towards any pony who tried to keep them apart. Something that could become violent and really dangerous, as one of them is a powerful alicorn.

Potion didn't know how this happened. She knew she didn't mess up her ingredients. She measured everything right. She was certain Cosmic harbored love for Gallant. But…what if she didn't? She tried every antidote potion she could, but none of them worked. What if she misread Cosmic's looks toward Gallant?

This was something her potions couldn't fix. She couldn't do anything to help her friends.

Scared and ashamed she decided to run. Using her potions she could hid her wings, but she herself couldn't hide forever. Not in Equestria. She needed to go somewhere else, and she knew where. A lake where one of the ingredients for many of her potions came from. She wasn't sure how, but she knew it will lead her somewhere else.

She took a leap of faith and disappeared into the lake. Where she went, only she knew.

After some time, she decided to return to Equestria. However, while only a few years passed for her, centauries went by in her home world. And Celestia had a new princess under her wings.

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Additional notes:

1. Love is something ponies thought can't be created trough magic or potions, as love (so is friendship) , so closely tied to ponies' power. This and other cases proved otherwise. However, the cases also showed that it shouldn't be toyed with, as a love created through unnatural circumstances can become corrupted and it was also outright wrong. So creating love spells and love potion became taboo. Information can still be read about them (hence why the love potion recipe was in Twilight's book), for historical and educational purposes.

2. The story of Princess Cosmic Prism and Prince Gallant changed over the centuries. The opposite happened to it as usually happens to fairy tales. It became darker. Details also have been changed.
Potion Nova was cut out, so it would be more a cautionary tale, to not try to force love onto others. And while there was a bit of a chaos, their kingdoms didn't fall. Their story's historical importance was only realized much later, by that time the changed details were lost (or hard to find).
When Potion Nova returned she was certain they couldn't broke her potion's curse. In reality Celestia managed to find ponies who figured out how to do it in only two weeks. Their names are lost to time, but one's name maybe had the word Spark in it, but who knows.

3. The incident created a rift between Cosmic and Gallant and it took years to mend. However, they fell in love with each other (in a natural, normal way) and got married. This is what really created Hearts and Hooves Day rather than the potion incident.

4. I mentioned love spells, so I need to bring up Cadance. While Cadance's special talent based around love, she can't create and force love. She can only mend already existing ones.

5. Twilight's spell in 'Lesson Zero' wasn't a love spell. Love spell only can be created between living beings.

6. Not just mirrors, but sometime other reflected surfaces can become portals to other worlds, if they gain magic from somewhere else. This is how the lake became a portal too (also why it became a good source for creating potions). Currently no plans for where it gained it's magic from.

7. Is this other world basically the world of Pony Life? Not sure, still thinking about that.

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Decided to add my favorite part from Pony Life into my AU. Which of course Potion Nova.

One of the reasons how this idea come about is how in some scene she was shown having wings (still no explanation why, wonder if ever even going to get one) , so I started to think about how she may be an alicorn, but she keeps it a secret. And than later I remembered the love potion and so on.

I also liked the idea of Celestia having multiple other students in the past.

I thought out more of Potion's story for my AU, how she becomes part of it, but for now I just wanted the introduction. But I can already tell the lesson of her story be something like 'maybe sometimes if you wanna help someone first talk with them'.

The name Princess Cosmic Prism and Prince Gallant may change later down the line (naming was never my talent). But knowing me they probably won't.X'D