One day after school, Sweetie Belle, Apple Bloom, and Scootaloo head to their clubhouse just like any other day. Today, however, they find a mysterious grey door has appeared in the back. Curious, they open it, finding nothing but a deep darkness inside. When Sweetie loses her balance and tumbles through, the other two dive in after her, beginning their new adventure across the multiverse in order to find their way home.

Deltatraveler by RynoGG
Undertale and Deltarune by Toby Fox
Undertale Yellow by Team Undertale Yellow
TG!History Recast by TG!Moonrose (that's me!), inspired by Andoro-T and Brenny114's History Recast
The Legend of Zelda series by Nintendo

Emerald Breeze, Descendant of King Sombra, lived a happy life with her family and her crush, Sekemoto. However, that all changed one day. After her world shattered in front of her, Emerald is left with a broken heart. Hopefully, however, these new ponies she's met can help heal her fractured SOUL.

This story takes place about half a year after MLP: The Movie. Anything that happened after in the show is not canon to the story, with a few exceptions (Ex. Spike getting wings).

After six months of living in Ponyville, Emerald Breeze and her SOUL-Sibling, Speda Hooves, are suddenly exiled from Ponyville due to their strange magic abilities. They flee to the alternate world through the Mirror Portal, and find friends, enemies, and more! This is the story of Emerald Breeze and her friends, trying to push through what life throws at them, while also trying to keep the world from tearing apart at the seams.

(This is an MLP story, with a slight change, in which characters can use the magic of the very essence of their being, their SOUL, to settle disputes. There are also Undertale references throughout, and a LOT of crossovers later on.
(Most of the tags will not come into play until later on in the story, where I will also leave trigger warnings.)
Story Arc Completion List for Book 1 (This one!)
•Melody Moon Arc: In Progress
•Siren Arc: N/A
•Rise of Sombra Arc: N/A
•Lost Love Arc: N/A
•Magic Arc: N/A
•Hurricane Arc: N/A
•De*TERMINATION* Arc: N/A
•Tournament Arc: N/A
•Crystal Arc: N/A
•Gun Incident/End of Book One: N/A