Aeons ago, tieflings were created when groups of humanoid races made a pact with an arch-demon or -devil, turning themselves and almost all their future offspring into the fiendish form known today. In the new age, it is no longer known for certain the specifics of how the tieflings came to be.
The tiefling trait is often suppressed in a family, but can never be removed fully, and tieflings are therefore sometimes born into a human family, where their heritage starts manifesting during adolescence. Conversely, a traditionally human family might embrace their lineage fully, which over time leads to their being only tiefling.
A tiefling has a devilish image with their tail and devil horns. The skin of a tiefling on Havilon ranges in dark red and purple hues. Tieflings born into human lineages often have human names, while some tieflings choose to take on a surname to signify a virtue or concept they try to embody.
The horns of a tiefling have nerves only at the base, like fingernails, and they grow until death. Some horns even split into branches, giving them the appearance of deer antlers. The especially vain among the tieflings keep their horns in check by clipping them on regular occasions.
As a race created by magic, tieflings have the innate ability to cast a selection of spells that might trace them back to their archdemon or archdevil of origin. Many tieflings typically teach themselves Infernal and favor Murk or Thrizur as a deity.