Board Thread:General Discussion/@comment-6192846-20130913170916/@comment-6192846-20140603113927

It seems contacts aren't necessary but beneficial to both parties, as it helps the user better commit their vices and it lets the demon have a greater range in committing those vices.

Without the user's knowing consent, most of these powers (which are manual) wouldn't be used and the demon would probably have to do what the Demon of Pride did to Kyle, forcibly transform them but make them go out of control(?), which seems to risk their possession being much shorter termed (army's attacking, mages exorcising, etc).

In the case of the Demon of Pride, it had possessed two of the most powerful people in the world (Riliane and Kyle) and didn't believe it needed to make a contract til reencountering Kyle in Heartbeat Clocktower.