I agree with headcanons that Hilda has a fear of rejection, and Frida of imperfection. But as for David and his many small fears; do you think there's a deeper phobia that acts as the common thread? Is it just a lack of confidence, or could there be a little more to it?
My reading is that it's ultimately a self-esteem issue? David lacks confidence in general because he lacks confidence in himself, and that has become a bit of a vicious cycle I think especially in Season 2 - he's actually very capable of standing up to frightening things for the sake of people he cares about, but when it comes to himself, he tends to fall into "I'm not brave enough" in a way that inflates his genuine fears a lot IMO, and I think the root of that is a general discomfort he feels around who he is and what he's capable of.
It's why I ended up headcanoning David/Lucy as transfem - it's very easy to read that lack of self-esteem and general discomfort in themself as a form of dysphoria or something approaching it, IMO - even though I know that's not the intent.











