Question: is theon greyjoy reek in the books?
Answer: In the books, there is a seperate character called Reek, who was Ramsay's servant. He disguises himself as Ramsay (during the events of A Clash of Kings/season 2) and gets killed, while Ramsay, disguised as Reek, infiltrates Winterfell. When he captures Theon, he names him Reek after his deceased servant.