Form

Demons tend to come in one of four forms.

Hitchhiker

A demon which attaches itself to a human host or hosts.

Artifact

A demon which takes the form of a magical talisman.

Incubus

A demon which takes a human form of its own.

Familiar

(change this term?)

A demon which takes the form of something clearly nonhuman.

Regardless of form, demons can communicate with their masters. Some demons communicate only basic emotions and images; others can do the whole devil-on-the-shoulder trick.