Guilty conscious
After Theon takes Winterfell, he expects to be received with open arms when instead he is seen as the villain. Because of this and because he wants to give the impression that he is in charge, Theon takes the decision to execute some of those who remained in Winterfell. Shortly after this however, he starts to feel guilty for the things he has done.
The Battle of Blackwater
When everything seems lost for King’s Landing, the King and his people are saved by Tywin and an army formed mostly of those who sided with Renly before his death. In the end, King’s Landing is saved by the people who were supposed to attack it and conquer it.
Brother-sister relationship
Theon is heavily mocked in the book because of his arrogance. Probably most of the most ironic episode regarding Theon is when he tries to seduce his own sister, unaware that he was recognized by his sister.
The court fool
After his Ser Dantos made a fool of himself showing up drunk at Joffrey’s tourney, he is made a fool as a punishment at Sansa’s request. Even after he was named a court jester, he still retained his identity as a Ser, but in a mockery way.
Betrayal
Roose Bolton’s bastard betrays Ser Rodrik when he believ that he will help them retake Winterfell and then takes advantage of Theon’s trust, convincing him to let them enter Winterfell which they burn to the ground after killing everyone.
