Sandor Clegane v. 9

[Silmarien]

I'm not sure why he (GRRM) hasn't given more background details on the Cleganes when people have asked him about them. Either they are not important so they don't exist or maybe they are part of the story that he doesn't want revealed yet.

I'd go for the latter. They are the most highly developed Bannermen to the Lannisters (as a family), and the brothers interact with and hugely impact major characters in the series:

-Sandor Clegane: Sansa, Arya, Joffrey, a number of secondary characters, incl. Tyrion, Beric Dondarrion/BwB, Thoros of Myr, The Elder Brother at the Quiet Isle, Ser Loras (saved his life a Hand's Tourney), Polliver and The Tickler

-Gregor Clegane: Arya, Cersei, Tyrion, a number of secondary characters incl the entire population of The Riverlands; BwB/Beric Dondarrion, Tywin, Elia Martell, Rhaenys, "Aegon" (random peasant child?), Oberyn Martell, Doran Martell, Sand Snakes, Dorne, Random Inkeep's Daughter (per Chiswyk's "hilarious" story :ack: )

That's a lot more than most Wardens'/Great Lords' bannermen are detailed (with the exception of The North).