Diyonic Tiefling

Tieflings are humanoids with size ranging from small to medium depending on their parentage. Facial shape and features as well as body shape is also more heavily influenced by whatever species are within the Tiefling's ancestry. Like Dragon-kin, Tieflings also sport at least one pair of horns in various styles, as well as a tail (though the Tiefling tail is decidedly less lizard-like in appearance).

Tiefling hair and skin come in an extensive range of tones and colors which appear to be tied with their magical connection to the Aether. Tieflings with fiery affinities tend to skew with warmer tones while those with affinities to things like lightning skew more into blues and purples. Of course, occasionally the opposite has been proven true so there may be no direct correlation.

Tertiary mutations related to a Tiefling's magical connection have also been noted in extremely rare cases including vestigial wings, symbiotic plant growths, and extra spines or other bone growths.

Tiefling genetics are maximally recessive but rather persistent throughout generational lines. In general, Tieflings appear in shape and form primarily as their parents (ex. a halfling tiefling is small and rather young in appearance while an elvish tiefling is tall and sharply angled) excepting their unique genetic traits. This appears to extend to pregnancy and gestation with lengths and risks aligning with the species baseline.

Tieflings are unique to other species in that couplings of two humanoids not including a Tiefling appear to be capable of giving birth of a Tiefling child. Inversely, it's reasonably likely that a coupling of Tieflings produce a non-Tiefling child based on their alternate ancestry (though minor affinities for a given magical element are still occasionally present among Tiefling born parents).

Tieflings grow and age at the same rate as their alternate genealogy, though they live about ten years shorter on average.

While it's unclear as to why, all Tieflings appear to exhibit dark vision. Many other species share this benefit, so in many cases it is attributed to shared genetics but even Tieflings born of humans and other diurnal races seem to have little issue seeing in the dark.

Tieflings appear to have an intrinsic connection to one of the magical elements, allowing improved control over the element as well as sensitivity to the element's presence or lack thereof. Unlike Genasi, who appear to be limited to the foundational elements, Tieflings appear to have no such limitations.

It is possible for Tieflings to shape their horns as they grow in. Such a practice is common in Torzma and Neroydia.

Tieflings lack their own language, instead learning from their parents.

It is said that Tieflings are the result of Alcara's corruptive magic or are, perhaps, descendants of Alcara's trysts with mortals (thus lending to their scientific name: Alcarus). It unclear how long Tieflings have been around as there are not very many of them and Tiefling history gets lost more-so than others due to lack of a cohesive culture.

Tiefling appearance resembles historical reference to the Goddess Alcara.

Other species views on Tieflings varies more with cultural belief than speciest generalization. Some view Tieflings as omens, both good and ill. Some carry the mistaken belief that a Tiefling child is the result of infidelity in the courtship. Dragons, uniquely, see Tieflings more often than not as closer to kin.

Tieflings typically come to understand rather quickly that they are outcasts even within their communities. This leads to many of them being cautious and sheltered but also to some being brash and daring as if to prove someone wrong. It's difficult to generalize as this group is so diverse.