Zelda as an Avatar: the Eye. Not in the observation sense, but in puzzle-solving - Zelda loves to figure things and people out, and digging for secrets and reasons, figuring out the way people work.

Zelda's fear is The Lonely. She's most afraid of being abandoned, of people forgetting about her — but also afraid of being misunderstood, and that she never will be understood. (This is also a flip of her as an Avatar, where she would be driven by the need to understand at all costs.)