Janus, the Roman god of beginnings and endings, passages and portals, time and transitions has experienced everything on Earth. He's witnessed it's future, he's studied it's past, and nothing could "wow" him. Humans were boring to him, they always did exactly what had played out in his visions. He needed a change of scenery, if only for a little bit. So he opened up doorways to entirely different places, dimensions, timelines. And he selected one at random. Turns out he can make some friends along the way.

To Equestria!