Josh reads her thoughts and gets the same odd language she's trying to speak, as well as random images. He says "food" and she thinks of the mangled biblically accurate deer she ate. He says "river" and surprise she imagines the river, but more like the bottom of it, where there are lots of river plants and what looks like freshwater eels? And more bones and shells of course. It's stuff like that until he muses about how she got in the river, and then Josh will see something of a memory:

She was in the lake west of here, swimming down the fogged-over part of the river, when the fog wall rolled back and trapped her outside of the lake. She tried to go back in, but as she's not powerful enough to slip through the fog on her own unlike the Guardians, she bonked her snoot into the barrier and was forced to relocate here.

Unlike when PCs try to slip through the fog without the golden glasses, though, she doesn't have a memory of taking psychic damage. She simply couldn't get back through to the other side.