A pretty self-explanatory title, heh? So! As we all know, there are many houses that are extinct by the time the series begin. The Greystarks - a cadet branch of house Stark - the Tarbecks, the Reynes, the Gardeners, the Durrandons, the Mudds, the Hoare... there are many of those.
If you could choose to learn more about one of them, which one would that be?