The Theon Greyjoy torture scenes in were some of the most difficult to watch. Theon was tortured by Ramsay Snow (later Bolton) for years in with the latter's motivations showing why he was one of the show's most twisted villains. Theon had an incredibly complicated journey in , playing both hero and villain at various points, but a large portion of his story was taken up by his being tortured by Ramsay. The torment inflicted upon him was one of ' darkest and longest-running stories, turning him into the broken Reek and establishing Ramsay as one of the show's biggest villains.
Though Theon returned from being Reek and even completed his redemption by the time of
The Theon Greyjoy torture initially came with a broader purpose for House Bolton, because, as he was a wanted
Ramsay torturing Theon and turning him into Reek has some added context in the books, where the first Reek was a man-at-arms from the Dreadfort, so-called because of his foul stench. Reek and Ramsay became close, engaging in all manner of cruelties with the former just as sadistic as his master. This included the capture and killing of Lady Donella Hornwood, who had previously informed those at Winterfell of Reek and Ramsay's behavior. That led to them being hunted by Ser Rodrik Cassel and his men. Reek was eventually killed by Ser Rodrik, who believed him to be Ramsay Snow.
The real Ramsay, pretending to be Reek, was taken to Winterfell as a prisoner, and remained there when Theon himself arrived to take the castle. He even served Theon himself after this, becoming an increasingly trusted ally (the idea of faking Bran and Rickon's deaths comes from him), before eventually revealing his true self when his men from the Dreadfort arrive to sack the castle. It's also possible, then, that Ramsay torturing Theon was also motivated by having served him; that the memory of having to be in that position made him even more determined to switch their roles and use Theon as his own servant.
, but Theon's arc wasn't among them. Theon Greyjoy had one of the strongest, most fulfilling journeys in , as he went from a relatively minor annoyance in season 1 to more of a villain in season 2 (albeit under the immense pressure to prove himself to others). From there he became the pitiful torture victim of Ramsay, then the savior of Sansa, the scarred man who left Yara with their uncle, Euron, and he eventually completed his redemption when , giving his life to protect Bran Stark.
There were a few redemption arcs in - Jaime Lannister's was another - but none were as satisfying as Theon's. A lot of that is due to Alfie Allen's performance, which combined with the storytelling, led audiences to fully invest in his development, rooting against and for him in equal measure. Theon being tortured by Ramsay certainly played its part in how viewers came to sympathize with him, but it was his actions after that, where he stood up and helped to save those he had wronged, that truly cemented him as one of ' great heroes in the end.
Theon Greyjoy's torture was very much a part of his character journey in George R.R. Martin's books, but it also differs in some key ways. The differences begin during in where he meets a lowly and filthy squire named Reek who served Ramsay Snow who was said to have been executed due to several crimes he committed in the North. When Rodrick Cassel brings a force of Stark men to surround the castle, Reek persuades Theon to allow him to sneak out of Winterfell and return with reinforcements. Reek does return with an army that wipes out the Stark army only to reveal himself as Ramsay Snow and proceeds to slaughter Theon's men as well and burn Winterfell.
Theon then disappears from the story in the next two books. However, one of the POV characters in Martin's most recent book is a character who calls himself Reek. Though the brutalized and traumatized character barely remembers his life before he was Reek, it becomes clear that this is Theon Greyjoy, transformed into Reek due to Ramsay's torture. While it makes sense for the show to keep Theon as a regular part of the show, the reveal of is very effective given that the audience hasn't heard from him for so long. In fact, seeing how much Theon has changed and imagining the torment he has endured is far more disturbing than actually seeing these moments on .