It's interesting that Dawn is afraid of Micah leaving, but not Nathaniel. Maybe it's because Micah is more of enigma?

I came at it from the angle that Dawn was picking up on Anita's emotions, and that Anita is more certain of Nathaniel's reactions than she is of Micah. Of course, the fact that she's tied to Nathaniel may have something to do with it.

that's my read of it, anyway.