From publisher blurb:
The tieflings hail from deepest reaches of the Burning Lands in the Dominion. The tieflings claim to be the first to have mastered magic and that their descendants ruled the lands as the first khans, a claim rejected by the Dominion authorities. The tieflings are human—or at least partially human—and part fiend. It is believed that in ancient times, creatures from the lower planes were summoned and bred with the local populace. Though it is generally agreed that the First Ones were responsible for this breeding program, the tieflings maintain they were the ones who encouraged this breeding. Tieflings are distant, aloof, reclusive, insulary, and devious. Most tieflings have a morbid fascination with death. They place great importance on their family and family ties, though they enjoy their freedom above all else. They consider females to be sacred vessels and blessed.
This sourcebook gives you everything you need to use the Sasori in the NeoExodus Campaign Setting as PC. Races of NeoExodus: Tiefling includes:
History of the Tiefling Personality, Physical Description, Relations, Alignment, Religion, Language, and Names
Tiefling Traits and Racial Subtypes