There is the fear itself, which if fed becomes a self-amplifying loop and can lead to complete overwhelm.
Then there is whatever it is that can sit and watch the fear arise, and which can also insert a needful brake: breathe, notice, breathe, notice, breathe...
There is the fear about present circumstances, and there is fear about possible outcomes or implications. Many different fear-flavors.
There is even a Book of Hours for fear, the fear of the early morning is not the same as the fear felt at mid-day or while trying to fall asleep at night.
Fear often seems tied to intense feelings of panicked attachment to or frantic avoidance of certain circumstances. Whatever it is we don't want to change might change. Or whatever it is that we don't want, will never change. Surprise! Thanks to impermanence, everything you don't want to change will always change, and nothing that you might fear will always stay the same.
Perhaps getting stuck in fear is because we forget about impermanence, even for a little while.
So can we make friends with impermanence as an ally to help us work with fear? To help us understand that no matter what we find at the root of our particular fears of the moment, it will not last?