The John Hopkins underhospital is not a particularly pleasent place, even by the standards of hospitals. It is not built deep enough into the earth that it can ignore the economics of digging underground spaces, and it was first dug more than a century ago, so it is cramped and warrenlike, every cubic meter at a premium, ceilings uncomfortably low and rooms uncomfortably small. Not everyone even has a room, the actual beds prioritised to critical patients, leaving longterm residents, patient and doctor alike, to sleep where they can, in hallways, chairs, and on desks in break rooms. People have built expansions, but they all end up the same way, with perhaps fewer patients driven to risk the light or the Deep proper for lack of a place to sleep. The underhospital is a liminal space, but one that can trap you forever, if you're not careful.
As the doctor moves through these halls, he sees a myriad of strangness that has grown a little familar in his time here - a shrine to the hospital god, surrounded by fresh flowers even this far underground, a man sleeping in a pile of bedding in a hallway, his left side replaced with a mass of mottled green-black tentacles, a monster-hunter lying wounded in a bed, his bandages tended to by a nurse with the huge nocturnal eyes and ears of a galago.
The hospital is something of a last resort - if you can't get the treatment you need on the surface, or you are a thing of the deeps already, you can come here, and perhaps you will find what you need. Perhaps it will keep you here forever - the dreams of the deep are all too likely to dissolve into nothing on the surface, and it can be hard to tell which treatments are too unreal to survive. The doctor has seen a man's every scar dissolve into open wounds from the touch of the sun (he lived, but only because the surface hosptial is just as good at what it does), and he has seen a woman with three limbs grown on trees walk unafraid under the sun, her wooden parts flourishing under the generous light. The deep is wonderful and terrible by equal measures, and those wonders can do things which nothing else can do, solve problems which would be unsolvable on the surface.
That is why the doctor is here, after all.