The Demon King's Sun Becomes An Eclipse

( This is a Muzan x demon Tanjiro fanfic with slight Giyuu X Tanjiro, don't like? there's the door →🚪)

Many years ago, it was said that a man once cursed to die, now forever immortal, ruled over creatures of the night in secret. This man was a demon, the very first demon born long ago in a time now forgotten. He had only two weaknesses, the sun, and his strange human lover, whom he'd first intended to marry as to find the blue spider lilies, the only thing that could cure his weakness. The fearsome demon who only feared death, would never have guessed he'd fall for this human. . .

Lord Muzan Kibutsuji was the name of this king of demons, and Tanjiro Kamado was his human lover, a beautiful man trained in demon slaying by his father. He was a kind yet strong human who saw compassion even for the demons he slayed, knowing they were once like him. Tanjiro knew his husband was a demon, even when he first met Muzan, due to his keen sense of smell.

Despite knowing this, Tanjiro married the demon anyway. Many have wondered why a human, raised to slay demons, would fall for the man known as the king of demons. An even more baffling question is how a human could become so loved by the king of demons, someone with great disdain for humans and how weak they are. Even so, demons knew better than to question such a thing. . .

Tanjiro was just like the sun. Even the human's appearance resembled the sun, with his long burgundy hair and dark red eyes. To Muzan, Tanjiro was the sun, his sun in fact, and only he could bask in his lovely glow. Everyone, man and demon, knew this. Yet one day, Tanjiro fell ill, only Muzan could sense his husband weakening. Refusing to lose the man he loved, Muzan turned Tanjiro into a demon, using the same medicine that changed him, as he wished for Tanjiro to keep his memories and kind nature.

But of course. . . Muzan couldn't have the man he saw as the sun, fearing the day's light. . .

Trigger warnings
Smut
Gay
Language
Blood
Death
Slight go