In the A Song of Ice and Fire novels, the Battle of Winterfell, called the Battle of Ice by GRRM and the fandom, still has to take place. Stannis doesn't march with just his army, as he has also secured the support of the northern mountain clans as well as that of Houses Glover, Mormont, half of the forces of House Umber and survivors of Houses Hornwood, Cerwyn, and Tallhart from the failed attempt to liberate Winterfell. Meanwhile, House Bolton enjoys the support of Houses Frey, Ryswell, Dustin, Locke, Cerwyn, Hornwood, and Stout (whose loyalty, except the Freys, is uncertain), as well as the nominal support of Houses Manderly, and the other half of Umber forces. The forces of House Karstark are also present in Stannis's camp as well, but they are actually in league with House Bolton.
The atmosphere in Winterfell becomes more and more hostile, especially as a result of series of murders. After a very bloody brawl between the Freys and the White Harbor men, Roose Bolton sends them to attack. He takes a great risk doing so, reducing the forces in Winterfell almost by half, but has no choice. As usual, Roose keeps the Bolton troops behind, hoping that the troops he sent will weaken Stannis's host. The Freys are delayed due to the trap pits that Mors Umber dug.
In a letter to Jon Snow, Ramsay Bolton, who believes Theon and his wife have fled to Castle Black, boasts of having eliminated Stannis's forces and demands the Lord Commander to hand over his bride, and his "Reek", as well as Stannis's queen and daughter. It is unknown whether the contents of the letter are true. Jon announces that he will go to Winterfell and fight Ramsay, and as a result he is stabbed by his own men.