There is no sun here.
Millions of miles underneath the Earth's surface there is only dusky, gray light. It has no identifiable source. It's as though it simply seeps from the air.
There are plenty of sounds though. Sounds you've been lucky enough to never hear in your human life. Sounds that have existed for eternity and will continue to exist even after every living thing on the surface of the Earth is gone. In the Fields of Asphodel there is the incessant, low moaning of restless souls. The souls wandering those fields cannot speak. The languages which separated them when they were alive no longer exist, but the memories do. They wander the lifeless grasslands all day (although the Underworld has no morning or night), searching for something familiar.
In Elysium, there is always the sound of running water and bubbling laughter. The smell of cooking food wafts from the island in every direction. Which was always curious, as the dead do not eat. Perhaps they like the smell. The Gods are the same way.
In Erebus, there are sounds which cannot be described. If you've never heard flesh being peeled from someone's bones and the accompanying scream that never gives way to unconsciousness, then let's hope you never will. There you will smell the thick, choking scent of burnt hair. The river of fire, Phlegethon, and the river of pain, Acheron, meet here.
Finally, there is Tartarus—the black abyss. Here you will find the most oppressing sound of all. Silence. It is not merely an absence of sound, but rather a heavy, penetrating quietness that presses down on you relentlessly. The pressure is so great that one finds they suddenly, inexplicably wish to cast themselves into the void.
The Underworld is no place for the weak, or the living. So why is there a young woman, breathing and alive, running through the Fields of Asphodel? Surrounded by an incomprehensible number of souls she looks so small; like a child frolicking through a field of cotton. She's afraid, and she should be, but she's also determined to make it out. To see the sun again.
What she doesn't see is the man in black, waiting for her only a few yards ahead. He wasn't there, but now he is. The dead skitter away from him, made anxious by his very presence. By the time they've cleared away enough for the woman to see the man it's too late. She's too close to turn around. She throws her hands up. Nothing happens. Her chest heaves with anxious breaths.
The man stalks closer, an aura of black clinging to him like a second skin.
"There's no magic here, Bon." He's close enough to reach out and touch her, but he merely offers her his hand. "None except mine."