"What dwells in the between?"

I have walked over the bridge

And seen the river that flows,

I have walked through the blue flags

And seen only shadows of frost.

The towering no longer stoop

And their heads: they’re no longer bare.

The tracks upon the ground are new

And the cold no longer seeps through.

Atop the mountain, I look out –

Out to the farthest, the fairest,

And tallest mountain of all:

Its heads are still bare

Its rivers don’t flow.

What dwells in the between?