Tieflings are more common in the Lastlands than they are in other parts of the Prime Material plane, though they are still fairly rare. They are viewed with mistrust in the Lastlands, although perhaps to a lesser extent than on other worlds. After all, the logic goes, there are few enough of the Common Races in the Lastlands and who knows what else out there. Better to tolerate your neighbor, even if he has horns and black irises and occasionally knicks a bottle of yak milk. That doesn’t mean that tieflings are looked on with kindness. They are talked about behind their backs and watched extra closely in shops and often called unflattering names, but they are rarely driven out of town at swordpoint.
Tieflings are also commonly involved with a number of Philosopher Cults. With their charisma, innate magic abilities, and link to the Outer Planes, tieflings are often the leaders of such cults. One of the biggest Philosopher Cults, The Ashen Path, is led by a powerful tiefling cleric named Dedication.