Rechan said:
I am a little disappointed that Demons are just "Kill destroy obliterate". That makes them pretty one-dimensional. Although I suppose that Demon Lords who plot could be looking to basically 'destroy everything' but on a more long term basis, more like anarchists and terrorists rather than simply arson or a murder spree.
In my homebrew, demons and devils are both fallen creatures, cursed to oblvioun at the end of time. The difference is in how they handle it. Devils seek to, basically, gather land (souls, planar real estate, raw magic power, etc.) in the hope of either taking over and changing the rules or getting the leverage to get the uber-powers that levied that curse to recant. Demons, on the other hand, have given up and accept their fate and are just trying to take as much with them as they can.
One of the PCs IMC is posessed by a glabrezu. Mostly, the demon rides or acts as an ally, but he's been known to punish her for misbehavior. He is masquerading as a magic sword (though the posession has moved from the sword to the mage) and has declared his intent to make the mage the most potent wizard on the planet. To that end, he gets her to trade certain tasks for certain favors. He has even convinced her to commit ritual human sacrifice and feed from the soul energy to rebuild (ala PHB2) some non-wizard levels to wizard levels.
How does this differ from a devil, you ask? Well, first of all, the glabrezu isn't interested in the mage's soul. He's interested in the destruction he can sow through her. People are more easily corrupted by another person than by an obvious demon, which makes more souls for the pit (oblivion). Also, this PC is right in the midst of a pretty significant event which could destroy huge portions of the multiverse. Since she's unaware of exactly the stakes she's playing with, the demon is wonderfully poised to push things just wrong. The position isn't really such that a land-grab is possible, so a devil wouldn't be interested, but it's perfect for a demon.
So, the demon is both motivated purely by destruction and a cunning planner with foresight. Works out nicely, actually.