Definition:
A demon is a powerful spiritual entity, often misunderstood as purely evil due to Christian influence. The true nature of demons varies by tradition.  

Etymology:
From Greek "daimon" meaning "divine power" or "spirit"—originally neutral or positive.

Different Traditions:

Christian View:
• Fallen angels.
• Evil servants of Satan.
• Tempters and tormentors.
• To be avoided or exorcised.  

Goetic/Ceremonial Magic:
• Spirits with specific powers and knowledge.
• Can be summoned and worked with.
• Hierarchies and legions.
• Neither purely good nor evil.
• Teach, protect, and assist if properly approached.

Andean (Supay):
• Spirits of Uku Pacha (lower world)
• Associated with transformation and death.
• Powerful allies when respected.
• Not inherently evil.

Demonolatry:
• Demons as worthy of worship or deep respect.
• Divine beings in their own right.
• Sources of wisdom and power.
• Mentors and guides.

Working With Demons:
• Requires respect and proper protocols.
• Offerings and reciprocity (ayni)
• Clear agreements and boundaries.
• Protection is wise.
• Different demons have different personalities and domains.
• Some are born assigned to work with specific demons.

Source:
Cross-traditional demonology, particularly Andean Supay work, The Syncretist Realm, TheSyncretistRealm.com.