Tiefling

“But you do see the way people look at you, devil’s child.” Those black eyes, cold as a winter storm, were staring right into her heart and the sudden seriousness in his voice jolted her.
“What is it they say?” he asked. “One’s a curiosity, two’s a conspiracy—”
“Three’s a curse,” she finished. “You think I haven’t heard that rubbish before?”
“I know you have.” When she glared at him, he added, “It’s not as if I’m plumbing the depths of your mind, dear girl. That is the burden of every tiefling. Some break under it, some make it the millstone around their neck, some revel in it.” He tilted his head again, scrutinizing her, with that wicked glint in his eyes. “You fight it, don’t you? Like a little wildcat, I wager. Every little jab and comment just sharpens your claws.”
— Erin M. Evans, Brimstone Angels

To be greeted with stares and whispers, to suffer violence and insult on the street, to see mistrust and fear in every eye: this is the lot of the tiefling. And to twist the knife, tieflings know that this is because a pact struck generations ago infused the essence of Asmodeus—overlord of the Nine Hells—into their bloodline. Their appearance and their nature are not their fault but the result of an ancient sin, for which they and their children and their children’s children will always be held accountable.

Infernal Bloodline
Tieflings are derived from human bloodlines, and in the broadest possible sense, they still look human. However, their infernal heritage has left a clear imprint on their appearance. Tieflings have large horns that take any of a variety of shapes: some have curling horns like a ram, others have straight and tall horns like a gazelle’s, and some spiral upward like an antelopes’ horns. They have thick tails, four to five feet long, which lash or coil around their legs when they get upset or nervous. Their canine teeth are sharply pointed, and their eyes are solid colors—black, red, white, silver, or gold—with no visible sclera or pupil. Their skin tones cover the full range of human coloration, but also include various shades of red. Their hair, cascading down from behind their horns, is usually dark, from black or brown to dark red, blue, or purple.
Self-Reliant and Suspicious
Tieflings subsist in small minorities found mostly in human cities or towns, often in the roughest quarters of those places, where they grow up to be swindlers, thieves, or crime lords. Sometimes they live among other minority populations in enclaves where they are treated with more respect.
Lacking a homeland, tieflings know that they have to make their own way in the world and that they have to be strong to survive. They are not quick to trust anyone who claims to be a friend, but when a tiefling’s companions demonstrate that they trust him or her, the tiefling learns to extend the same trust to them. And once a tiefling gives someone loyalty, the tiefling is a firm friend or ally for life.