Tieflings

Tieflings are mortals with infernal power tied to their blood. While Aasimar bear only slight marks of the celestial when not manifesting their aspect, tieflings are always obvious. Although often called hell-spawn or devil children, tieflings are created as the result of pacts sealed with one of the more powerful Devils of the Hells, usually an Archdevil or their representative.
Such pacts are called vinculi inferni, and grant minor gifts in exchange for binding infernal energy into the pact-maker's children. The more children in a generation, and the more generations that are offered, the greater the gifts offered. The horns, skin colour and tails of tieflings are the marks of the vinculum. They grant no power over the children - contrary to some folk tales, a parent has no standing to bargain the souls of their children - but the fear and suspicion that they provoke can drive tieflings to accept their own devil's bargains.
The physical union of devil and mortal is possible, but produces the offspring known as cambions, who are physically similar to, but both much more powerful and more inherently drawn to disharmony and evil than tieflings.
Tieflings principally acquire their identity from the mortal society into which they are born, but they attract a great deal of scorn and distrust because of their appearance, especially in areas where cambions have openly operated in the past. Their unique nature derives from the realms of law, and while some embrace the call to order and rule, they are more likely to reject that, along with any other sense of obligation to their progenitors, and deliberately infringe on societal norms. This does not help to diffuse suspicion towards them.
Because of their origins, tiellings are widely distrusted, and agents of the Hells will gladly take advantage of this by offering aid and succour to tieflings targeted by prejudice and discrimination. Such aid is often traded for extending the tiefling blood's duration, and by unspoken extension, the number of vulnerable descendants who might be willing to make a deal in time.
All tieflings have horns, muscular tails which range from half to as long as they are tall, and digitigrade feet. Other common, but not universal, traits include hoofs or hoof-like toes or eyes which are a single, solid colour, with no whites or pupils. While some bear the normal skin and hair colours of their mortal parentage, others have marked signs of their infernal heritage in the form of red, purple, chalk white or coal black skin, and either very dark or very fair hair. Other traits vary, and reflect the nature of the Archdevil in whose name the pact was made. This is known as the tiefling's 'mark.'

Infernal Marks

Mark of the Absolute

Tieflings bearing the Mark of Ultima the Peerless, Prince Absolute of the Nine Hells are rare, as the Absolute rarely makes deals of the sort that create tieflings. Usually born to those already possessing a measure of material power, these tieflings tend to be large and imposing, and inherit dark colouring and heavy, hoofed feet. Their hair is fine, or absent entirely, and they often sport between five and nine small horns in a symmetrical arrangement. Those with nine horns, mirroring the nine-pointed Crown of the Hells, are viewed with particular suspicion. The powers of this Mark allow a tiefling to impose their will on others.

Mark of the Archscrivener

Devils in the service of Omphala, Archscrivener of the Grey Clerks, make pacts solely because it is their nature and business to do so, thus tieflings bearing the Archscrivener's Mark can be born into almost any background. The Mark typically manifests in one or more of gracile, cloven hooves; dark hair; fine, almost elven features; silver eyes without pupils or whites; and dark markings on the skin which resemble letters of an unknowable script.

Mark of the Bloodbane

Robust and fierce, tieflings who bear the infernal legacy of Astolat the Bloodbane, Mistress of the Right-Hand Spiral sport powerful wings to complement their horns. Other common traits include clawed, semi-prehensile feet, barbed tails and prominent, sharp teeth. These tieflings are rare in the material World, because the pacts which create them are usually offered to the desperate in return for their child's service in the defence of the Nine Hells.

Mark of the Doomhammer

Pacts with the devils of the Soulforge Foundry are typically paid with service at the anvil, and so Tieflings who bear the Mark of Fulmar the Doomhammer, Grand Master of Infernal Arms, are usually born to master smiths. They carry the scent of the forge wherever they go, and have an inherent ability to call forth armour and blade. Red or black skin is a common trait; others include perpetually blackened fingers, a lack of hair and a flicker of flame in the eyes, regardless of their surroundings.

Mark of the Fallen

Pacts sworn by devils of the Bloodwing usually demand service in the Deep War, but are often made simply from spite, to see others fall as they once did. The Mark of Imrael the Fallen, Commander of the Bloodwing, mocks the divine as much as it grants strength. Fierce and unrelenting, tieflings bearing this Mark wield their heritage as weapons. Common traits include blood-red skin tones, horns which curl into a mockery of an angelic aureole, and occasionally narrow, feathered quills interspersed with their hair.

Mark of the Greyshade

Typically mild and unassuming, at least by tiefling standards, those born with the Mark of Bleys Greyshade, Whisperer in Darkness, possess powers which can aid them in the pursuit of secrets. Such individuals are also born from secrets, the pacts which create them invariably sealed by some exchange of information. The Mark manifests in white, silver or grey hair and a marked palour, even on otherwise dark skin.

Mark of the Mirror

The devils of the Labyrinth make pacts in pursuit of their own convoluted ends and are known for deceit and treachery. These pacts are often generational in nature, and many tieflings bearing the Mark of Q'Vas, Marquis of Mirrors and Lord of the Eternal Labyrinth, are born into cults serving the Marquis. Ghostly pale, their powers are those of deception and discovery. The Mark manifests in pale, almost translucent skin, and very pale eyes and hair.

Mark of the Once-Divine

The infernal legacy of Illuvis Once-Divine, Light of the Aurora is often granted to those who have returned escaped souls to the custody of the Hells. The Mark manifests in a radiant beauty, coupled with powers of light and seeming. The hair, skin and eyes of these tieflings, regardless of colour and tone, often have a golden sheen, and their toes often bear soft, cat-like pads.

Mark of the Scribe

Born in exchange for information, tieflings carrying the legacy of K'ao-zzin the Scribe, Prime Actuary of the Dark Ledger have insectile features, such as large, almost oversized, eyes, antennae-like horns, and chitinous spurs at their joints. Their feet may also be insectile, with long, chitin-sheathed toes. These tieflings are given powers to find and relay information.

Mark of the Silvertongued

Like her sister archdevil, Diyah the Silvertongue, Mistress of the Left-Hand Spiral, seldom makes pacts that do not benefit the defence of her realm. Silvertongued tieflings are gifted with powers which help them avoid or evade conflict, and many are pledged by their parents to the service of the Fathomless Vertex as diplomats and spies. Their Mark often manifests in delicate, golden hooves and horns, as well as a certain grace of movement and bearing.