Vortexes are overused, couldn't you come up with something more, not normal. Like, falling into a mirror or falling down a well? Sorry if you've been offended, this is just an opinion, not a flame. Also, could you try and make the chapters longer?

How can one not be an obsessive Avatar fan? P

Interesting start, I look forward to reading the rest.

The only thing is the switching POV in the middle of a chapter. It's just a bit convoluted in the transition. Maybe you could write each chapter in a different POV and alternate. Maybe you've already thought of that, but just a suggestion to help the flow.