Help me remember what audiodrama that is

Usually my memory for this kind of thing is nearly perfect but apparently not this time so I need a little help.

I remember a male or nonbinary character (the main character) who talked and told stories to an entity in a tunnel (I think?) and considered them a friend. The entity had a female-sounding voice afaik and was a human-eating one but had some sort of an agreement with the MC to keep it at bay. Part of the said agreement was that the MC cannot look at the entity when it comes out to the edge of the tunnel to talk. And I think at some point it threatened to or actually did break the agreement?

I think it might be Jar of Rebuke but am not sure, help me out pls?