Dragons are clever.
Dragons are charismatic.
Dragons can have powerful will-twisting magic.
All of this screams "minions" -- so who are the dragon's minions in your campaign? Agents of influence, defenders of the lair, people to make PCs have a horrible time going up against the dragon... add yours to this thread! And are there any twists on the idea?
1. A charmed warrior of great skill and little wits, equipped with the best weapons and armor of those who sought to slay the dragon (i.e., PC-level wealth).
2. A deluded princess. (Twist: she's not deluded, she's trying to sneak into the dragon's good graces to steal something in its hoard.)
3. A outsider who shows up periodically to play chess with the dragon and is also philosophically opposed to one or more of the PCs. (Twist: Or would be simpatico with one or more of the PCs if they weren't out to kill his buddy, maybe he wants to try and mediate.)
4. A bard who is composing songs in honor of the dragon and interviewing him to make sure all the details are right; naturally he'll help the dragon fight so he can get more song material. (Twist: he's also a fanboy of the most famous PC.)
5. An elderly druid who belongs to the Society for the Preservation of Endangered Dragons. (Twist: he's actually there as a matchmaker from another dragon.)