It’s true we haven’t seen a Grey DeLisle character yet and she did say she was playing a Dark Spirit.

As of this moment, my best guess is that Vaatu was trapped in his Spirit Tree at least up until Unalaq could physically get in there during his brief “The Sting” scene.

Unalaq also has some erroneous ideas about the history of those Spirit Portals. Assuming what we saw in “The Beginning” was true, Unalaq’s talk about how the Water Tribe used the portals to move back and forth probably isn’t. Unalaq also has some sort of spirit calming power we haven’t learned the details of (it makes sense the Avatar can do it because s/he’s just using Raava to change the spirit’s mood).

Overall: it seems like Unalaq has SOME idea of what’s going on. 

What seems likely is that there is a middle-man dark spirit, possibly the Dark Spirit Grey DeLisle is voicing, that is working with Unalaq as an agent of Vaatu. Like a Wormtongue or a Saruman. 

A serious middle-bad, but a mini-boss compared to the apocalypse that is Vaatu. 

Or Grey DeLisle and everyone totally got us and Azula’s still alive. That could be fun.

-Da7e-