Dreamers have a great deal of power within the dream, able to create, destroy and control at a whim, although within certain constraints. In order to keep the dream a consistent multiplayer experience for all dreamers, they cannot effect each other directly, and if they attempt to do two incompatible things, the software will try to combine the two actions, often with unexpected consequences.
Some dreamers are more lucid than others, and even lucid dreamers have unconscious influences. Observing in the local dream can be a good way to gauge local feeling, and a lot about a community can be determined by tracking changes in their dream.
Plot Hook: Firewall needs information from someone, but cannot simply abduct and interrogate them. They are, however, a dream user. The players must subscribe to the dream, track down the appropriate dreamer and interpret their dreams, looking for clues.