Aight. I was playing with the idea of having one of the villains as this Metal Bender who has proclaimed himself king of the Earth Kingdom. Residing in the ruins of the modern Ba Sing Se, he's rumored to have the greatest single force in the land. His main source of income would be banditry, or tithes he has forced other settlements to pay. 

But how does my character discover that your guy is the Avatar? We gotta figure out how they meet and stuff.