But that's the thing: Fairies are magical and walruses are mundane.

As mundane creatures walruses need to have a mundane explanation for everything they do. Leading to the mental gymnastics above.

Fairies are magic. You know the old rule of magic:

This answers all the questions about the fairy you might have beyond "Why does the fairy want to talk to me?" but that's a question that applies to any stranger and isn't a big surprise.

Every single thing assumed of the walrus requires a similar if not identical assumption for the fairy, before needing to ALSO reckon with every sprawling implication of the revelation of the existence of a sapient, nonhuman, supernatural species on Earth.