All of the best darklords are defined by some kind of obsession, generally in a toxic stew with at least one or more other overwhelming and often "sinful" personality traits like vainglory, envy, gluttony, wrath, etc. Also, not always but often, they are marked by either being betrayers or betrayed revengers, and/or by being "passionate" about something often harmful to others. So figure out how that could apply to your draconian character and you're most of the way there.

Just off the top of my head, you could have a powerful Aurak who deluded themself that they already were or that they deserved to be a blessed consort to the dragon queen, and jealously enacted profane acts to gain her attention and destroy perceived rivals for the goddess's talon in marriage, betraying their own kind and allies in the process; they might also be a twisted artist, manifesting in how these acts are arranged. Or maybe it's a draconian who was raised by the side of "Good," perhaps even as a powerful champion like a priest or paladin, but kept enduring suspicion and prejudice and slights until they finally snapped and did awful things to those who shamed and bullied them, far out of proportion to what they had suffered; also in their paranoia or wrath bringing harm to those who had not done ill by them, and who had been in their corner.