Here's an idea I wrote for Shadowfell, could work with Hades or the Plane of Shadow:
The Gloom Boxes: The Gloom Boxes are a collective term for the jails, asylums, and most unfortunately orphanages and refugee camps that simultaneously exist in the world and in the emotionally draining glooms of the Shadowfell. Designed to make the charges within their confines more tractable, many of these facilities are now haunted ruins left in disrepair.
I hung upon that windswept tree for nine days and nine nights, pierced by my own spear. I stared into the void between and beyond all things, until I spied the runes and seized them up. And howling, I fell.
Some members of the Seelie Court occasionally visit this far off corner of the Gray Waste for reasons unknown. The passion of the fey affects even this emotionless plane, mingling with the underlying despair to create an area of bittersweet melancholy.
What are these? So wither’d and so wild in their attire, That look not like the inhabitants o’ the earth, And yet are on it? - William Shakespeare, Macbeth
Strangely enough, one of the sobriquets associated with Bel Aloth is ‘the Serene One.’ This ultroloth has not once – at least, not any time in recent history or recalled memory – displayed any sign of strong anger, fear, hatred, or any other powerful emotion. Everything, to Bel Aloth, is a tool to be used, a situation to be manipulated, or an obstacle to be overcome.
“Some years ago, when the Blood War still filled my head with notions of glorious, bloody violence, I became one of a rather small number of mortals to ever visit the Screaming Pillars of Oinos. I actually survived to tell the tale.