Assuming neither of them ended up becoming the eldest living son (that is, had Robb Stark survived to adulthood), what was expected of the younger Stark sons, Bran and Rickon?
As I understand it, Robb, as first born male, would inherit the titles of Lord of Winterfell and Warden of the North, and all the land of Winterfell to go with it. The girls, Sansa and Arya, would most likely be married to secure alliances with other powerful houses. Jon, as a bastard, wouldn't have had many useful prospects, which is a large part of why he decides to join the Night Watch.
But what about the other two boys?
I checked on the Game of Thrones wiki for a while but I saw no information about what the younger Starks were supposed to do when they got older. Would they inherit "smaller" portions of Winterfell or the north? Would they need to marry themselves to another house in order to "earn" their own "domains"?