Plague doctor.

Demon horns being broken halos from when they were angels. 

Here’s a visual representation of angels and demons.

I figure that as angels, their “horns” would glow when connected to become traditional halos. However, this blinds the angel with heavenly light, making the angel rely on God’s guidance.

Angels who break their halos become demons, and willingly grow their horns in obscure shapes so it won’t connect back into a halo. Because the halo no longer blinds them, demons can finally see but can no longer communicate with God for guidance – the light they once gave to heaven now belongs to them, hence demons being proficient with fire allowing them to see in the dark.

Extra notes on horns & halos:

Circular horns (Halos) are smooth and easy for God to “grab” like a chain.

The only way angels can break their own halos is through strong, direct, hard force; rebellious angels willingly fell from heaven, breaking their halos upon hitting our world’s surface. That’s why demons are called “fallen angels”.

The only thing that can hurt God and other angels is another angel, so the shattered remains of a demon’s old halo would be reformed into tridents and pitchforks commonly associated with the devil.

THATS NOT ARTIFACTING. THATS THE BODY SWAYING.