Tieflings are the descendants of the union between a devil and a human. Though they are not devils themselves, nor are they inherently evil, they are nonetheless greeted with mistrust nearly everywhere they go. While tiefling travelers are usually tolerated, provided they do not stay for long, few communities will accept a tiefling living among them. Most tiefling therefore find themselves to be outcasts, and many turn to less-than-legal professions such as thieves and assassins. This is not due to any sort of intrinsic predisposition, but a vicious cycle in which those who expect them to be criminals rarely allow them the opportunity to be anything but.
If any region can be truly said to be friendly to tieflings, however, it is Estorium. There, tieflings are judged the same as everyone else: not by their heritage, but by their magical aptitude. As a result, tieflings are somewhat more common there than in other parts of Syra.