Looking for tips on dragons in humanoid form

[Arbiter of Wyrms]

When I first created my campaign world years ago, the city where the campaign was focused included no less than three dragon NPCs in human form:
• A great wyrm gold dragon who appeared as an aged human wizard served as a sponsor to several groups of adventurers.
• An old silver dragon who poses as a priest of Dionysus and sometimes raises eyebrows with his heterodoxical doctrines.
• A young adult steel dragon (Greyhawk dragon) who, generally unaware of his true form, served as the city's mayor.
Because the steel dragon was so fully immersed in his role as a human, the other two initially dwelt in the city to safeguard him against potential draconic enemies with he would not have realized he was able to cope.
As it turned out, a group of PCs took a contract from a thieves' guild/cult dedicated to a deceased black dragon to assassinate the steel dragon. One overconfident halfling rogue versus the (presumed human commoner/expert) mayor while the half-orc mulcher stood guard outside. The human form was easily dismissed with a single sneak attack/coup de grace, leaving a somewhat surprised halfling rogue facing a dragon by himself. The dragon was even more surprised, though, to remember that he was in fact a dragon, and not a human being. A series of abberrant roles, my inexperience as a DM, and the complete abscence of challenge ratings in AD&D left the halfling victorious and with an even more inflated self-image than he had before.
The gold dragon's patronage of advaenturers has lead him to all sorts of new embroilments, but functionally, I play him as I would any other human archmage benefactor - mysterious, omnipotent, aloof, but kind.
The silver dragon, disheartened by the failure to protect the steel (an endangered species) and bored with his role as leader of a large congregation of humans and elves, prepares to move on to a new identity and a new community.

 

[Psion]

Motivation for such dragons seem pretty straightforward.

They are good; I read this as altruistic. Those that bother to assume human form may be rather patronly as well.

They may assume their form to disguise their movements and involvement from enemies, and avoid alarm in humanoids.


I typically create alter egos for dragons that don't compromise them using their non-physical abilities and knowledge. In my last game of my River of Worlds campaign, I had two silvers show up at the site of a village destroyed by a red dragon enemy of theirs. They disguised themselves as priests, in priestly robes which I described in some detail, along with the silver hair. The hair is a little tell I use in my game... polymorhped dragons always have hair the color of their scales. Nonetheless, the players didn't pick up on this, and the priests spellcasting and knowledge was accepted by the party without a blink.

I've also cast dragons in the form of monks, sages, and hermits.