One thing I like about nWOD Demon is that it keeps the demonic 'feel' while changing all the reasons why they're there.
Demons are consummate liars, not because they're creatures of sin but because their minds have no subconscious; every expression down to the micro-expressions are acts of choice and will. They can be sincere, but no one can tell if they're sincere because the would never show as anything but sincere unless they wanted to appear insincere. Its part of why trust among demons is hard.
Demons make pacts! Only, its not some currency in hell, or for souls (really). Instead, what a demon wants is a part of your life. You have a stalker ex? Why, you let the demon take him off your hands and in return they get something (anywhere from a 1 or 2 dot merit to an 5 dot merit for free). The contracts edits reality and now that ex is stalking the demon. Why would a demon want a stalker? Because it makes his cover stronger, and this is a really easy pact to offer: it seems to the human the cost is a benefit. Now... down the road, the next time the demon makes an offer and this time he wants something more...
A demon can make a soul pact, but the humans never really understand what that means. When it comes time for the demon to call in the soul pact, they take that person's entire life and it becomes a complete, new cover. The demon slips straight into their fully formed life: this is the best kind of cover. The person ceases to exist utterly.
rambling I do love this game.