The deities with the most limited and specialized domains are often called "minor divinities" or "demons" in modern writing, although there is no firm definition for these terms. Some demons were guardians of particular places, especially in the Duat, the realm of the dead. Others wandered through the human world and the Duat, either as servants and messengers of the greater gods or as roving spirits that caused illness or other misfortunes among humans. Demons' position in the divine hierarchy was not fixed. The protective deities Bes and Taweret originally had minor, demon-like roles, but over time they came to be credited with great influence. The most feared beings in the Duat were regarded as both disgusting and dangerous to humans. Over the course of Egyptian history, they came to be regarded as fundamentally inferior members of divine society and to represent the opposite of the beneficial, life-giving major gods. Yet even the most revered deities could sometimes exact vengeance on humans or each other, displaying a demon-like side to their character and blurring the boundaries between demons and gods.