In the old World of Darkness game Changeling: the Dreaming, no specific banality rating is given for demons (as in Demon: the Fallen)? What is an appropriate rating, and how is that rating justified by the lore?
The sensible answer would be that they have a low banality (banality means the denial of awe and wonder and demons are really unlikley to do that) however the same is true of vampires and they always had high banality despite this not making sense in light of the in game logic.
If you want to go with the feel of Changeling's themes and mood then give them frighteningly low banality scores (these are the creatures who basically set up creation and everything within it after all, they won't be denying the supernatural and the fantastic). If you are trying to guess what the Canon suppliments would have said, give them Banality on the same levels as Antedeluvian Vampires.
That being said, rememebr that the Demons of Demon: the Fallen do not exist in the World of Darkness of the 1st and 2nd editions (and thus there are no real Changelings in the Demon: the fallen setting). You would be better using the traditional Demon's of the old World of Darkness setting itself (found scattered around the 1st and 2nd edition books, especially V:tM and M:tA). These Demons (who grant investments and are not specifically tied to the Judeo-Christian paradigm/dogma) will work much better in a Changeling game. Their banality will be more akin to the banality (or lack thereof) of the Banes and spirits of Werewolf/Mage.
Actually, I think they should have more banality. Explained by the three ‘gods’ of WoD (create, maintain, destroy) as in Werewolf (Wyld, Weaver, Wyrm), the angels are both the creators of reality (Wyld) and the maintainers of it (Weaver). Anything that remotely falls upon Wyld have lower banality (such as malkavian vampires) and anything that remotely falls under Weaver has higher banality (such as technocracy mages). Wyrm entities, thus shuld have lower banality in game terms (they normally do not deny the supernatural as there are fewer things less supernatural than Baali, Nephandi or anything of the lot), they have medium-rate banality.
I think they should have more or less like 7 banality (could be 6, though), and dropping one or two points for the ‘Wyld oriented Demon’ and going up one or two points for the ‘Weaver’ oriented ones.
I think that banality is not on the ‘supernatural believe’ side but more on the ‘rational’ part of this supernatural entities and how they attach themselves to ‘Weaver thoughts’ such as technology, logic and systematic solutions. The more the rational, the higher the banality.
Looking at vampires, mages and werewolves (the other supernatural creatures when changeling came out) it seems obvious that it does not depend on the believes of the supernatural (since all of them believe in the supernatural), since there are supernaturals (that firmly belive in the supernatural, not that they are in denial) that have high banality such as 8 or 9 (even 10).
I've been trying to stat NPCs for a demon game I'm running. It seems to me that a demon's banality should be their torment score. Torment reflects madness and hatred but also a losing of the angelic, innocent side. Earthbound and other truly monstrous fallen have a torment of 8+ while freshly escaped demons have a torment of 3-4 and angels have torment of 0.