Ahh reading this the adaption kind of makes more sense
David Benioff noted during the airing of the second season that they would delay the introduction of several key characters first appearing in A Clash of Kings until the third season, citing the large number of characters already introduced in season two. Dan Weiss added that they couldn't afford to have people "waiting around" for their characters to become central to the plot.
I'll put the list of chars inside a spoiler just incase, although it doesn't really spoiling anything.
Mance Rayder, the Wildling "King beyond the Wall"
Tormund Giantsbane, a Wildling raider
Daario Naharis, a Tyroshi mercenary captain
Jojen and Meera Reed, two young Crannogman siblings
Edmure Tully, Catelyn Stark's brother
Brynden Tully, the "Blackfish", Catelyn's uncle
Selyse Baratheon, Stannis Baratheon's wife
Shireen Baratheon, their daughter; cast with Kerry Ingram[8]
Olenna Redwyne, the "Queen of Thorns", Margaery and Loras Tyrell's grandmother
Beric Dondarrion, the leader of the "Brotherhood without Banners" (the character already appeared briefly in a scene in season 1)
Thoros of Myr, a red priest with the Brotherhood
for me blackfish is one of the most likeable characters although hes not a POV character, will be interesting to see who they cast for these roles. hope we get info come out like last time to make the 10 month wait more bearable.