This right here is an awesome adventure story about a teenage girl, named Jennifer, who had a human Pinkie Pie as a babysitter before mysteriously disappearing off the face of the Earth a couple of years ago. Later in the present, after following human Luna through the forest thanks to her connection to Pinkie Pie she finds out that when beings cross over to another dimension they change into the dimension's dominent native species the longer they stay in the dimension and if they stay in here even longer, they'll become trapped in that dimension and their new form forever. Now that the girl has entered Equestria, she too is succumbing to the affects of the dimension's unwritten rule to become a native's dominent species, a pony, a unicorn pony to be specific. Even though it shouldn't matter since the door back to the real world is pretty accessible, but it turns out things are not always this easy. Discord was responsible for "leaving the portal" open for the girl to enter and has turned most of the mane cast into toys and wants her to find certain items. Luckily, Jennifer made a bet with Discord to race towards with three companions to look for these items and whoever finds two of them wins. But Jennifer has a time limit to find these items first or else she'll go full pony and then (sometime later) be stuck in Equestria forever.
It's a slow transformation adventure story about a girl who is slowly becoming a pony while in Equestria on a race to find the Macguffins with three of the mane cast before Discord. It's definitely a great read, you should check it out.
https://www.fimfiction.net/story/740...est-babysitter