Council of Thieves
Tieflings are the offspring of a human and a devil. They usually look just like normal people except for the maybe the odd characteristic. Sometimes the devil blood runs deeper and they have small horns, or pronounced fangs or claws.
They are very rare, and one usually doesn’t even know that they aren’t human. However, given the current religious climate in the Red Empire, rumors of tieflings are becoming more common. Witch hunts would ensue except that any true tieflings would likely have support from the Imperials.