Eighis and Adhy are both live in the Earth Kingdom and they're both benders. Metalbenders. Adherent is a scholarly type. Cheerful, mildly eccentric, occasionally acts like a whirlwind on two legs, but generally seems harmless. Key word here being "seems". Pick a fight with him and you'll find a maniac with two swords, one who is also a damn good metalbender to boot. (Though he favors precision and control over sheer power.) And sometimes he criticizes various governments, just for kicks. He also used to travel a lot. Never stayed in one place for long, him. He doesn't do that anymore. More on that in a bit.

Eighis is Bharal's brother. [There probably isn't a very big age difference, but I'd still like to know which one is the older one and which one is the younger.] Eighis is also Adherent's nephew. Adhy probably hadn't even met his nephews until after the boys' parents died. [Details like "how?" and "when?" still need to be hammered out.] Adherent (and Sentinel, who [I'm guessing] is also an uncle, but on the other side of the family.) ended up taking Eighis and Bharal in. And that's why Adherent doesn't travel anymore.