For so long, Sansas hair changed season by season depending on who was influencing her, the first few episodes she was a Northerner in Winterfell and took after her mother with a simple braid down the back. Then when she went to Kings Landing it was a big, decadent halo that was very much like what the Queen wore. With Littlefinger, she dyes her hair black and wears all black. Then she goes back to Winterfell and returns to her mothers hair.