all hail princess sea swirl!

A pretty interesting story. I recommend giving it a look.
 
For summary – Flurry’s attempts to teleport cause her to accidentally phase to a Human Dimension ^(tm), where a hapless human passerby picks her up and brings her home without really knowing what she’s supposed to be. An increasingly distressed Flurry eventually decides she wants her mommy, and being the human the closest person around her he gets accidentally turned into the alicorn up here. This eventually draws the attention of a couple of of groups seemingly as knowledgeable as they’re secretive, who offer to help with his problems with… probably less than altruistic designs.
 
Meanwhile, in Equestria, Twilight’s got the privilege of juggling the rescue attempts (they don’t know which universe Flurry ended up in, which complicates matters somewhat) and managing an increasingly desperate and frantic Cadence.