Admit it, no one knew that this ship was going to happen: Startrix

One day when Pinkie Pie was trying to dance for a party one day and needed a dance partner and she tells Fluttershy and she agrees to dance with her. When they finish the dance, they end up fusions.

When the mane 6 find a mansion out in the Everfree Forest, they decide to explore. And it's the worst thing they have ever done.