Demons are interesting dream characters. Whether you view them as psychological constructs or ontic reality in your view of the cosmos, their presence is a significant statement. The meaning of the demons revolves around their power relative to other major characters in the dream.
Demons may have seductive or violent power in a taboo relationship to the dreamer as either a nemesis or helper to the cause of the dreamer. In these cases the dreamer sees him or herself as helped or hindered by supernatural powers in the accomplishment of a moral or personal conquest.
If a demon is helping you complete a task, it may say something about how your task is viewed morally either in your superego or in the structure of the spirit realm. If a demon is thwarting your progress, this may reflect your perception of evil working against you in your life. If the demon is threatening others who are important in your life, you may be struggling with how to protect or provide for others in a world perceived as hostile.
If the demons are helping you acquire something you hold as taboo, some self-examination concerning motives may be appropriate. Are they powerful in an alluring or repulsive way?