Well, the second book ended with Osha and the Reeds splitting up Rickon (with Osha) and Bran (with the Reeds to continue his warging training) and going off in opposite directions when Ramsey Snow took Winterfell from Theon, But since it looks like the Reeds aren't in the show, Osha's sneaking the boys (with Hodor, of course) out of Winterfell seems like it's the new version.

Sansa's time in this season is done, as well, as the last scene with her in Clash of Kings was when the Hound drunkenly offered to get her out of King's Landing before making her sing at knife point, then left her alone with his gold cloak after, in Sansa's mind, giving her a small kiss on the cheek.

Arya escaped Harrenhall with Gendry and Hot Pie, but after she recalled Jaqan Haqar's name (she opted to have him help certain prisoners escape instead), he changed his face before her (since he is a Faceless Man, Jaqan Haqar is merely a disguise for him), and gave her a coin to get her to the Faceless Men guild at a later time. She uses that coin to kill a guard blocking her escape route (she dropped it on the ground and slit his throat when he bent over to pick it up, much to Gendry's horror, and she was really calm when he said "You killed him?!"

Robb wasn't seen after the Battle of the Blackwater (he didn't participate, as his forces were still in Riverrun), so I think his time is done this season.

Jon still has one more part to play. Originally he and Halfhand were captured together while fleeing from the Wildlings (the show hasn't deviated much here). Jon was told by Halfhand to "betray" his oaths to figure out what Mance was up to, and to prove himself a "traitor's bastard", he kills Halfhand to show he really defected.