While Tyrion Lannister still kills Tywin with a crossbow in Game of Thrones, his reason for killing his father was changed from the books. When adapting the series for television, HBO’s Game of Thrones made several significant changes to character backgrounds, motivations, and major plotlines from George R.R. Martin’s A Song of Ice and Fire books. From cutting Cersei’s prophecy about the valonqar, completely leaving out the survival of Rhaegar’s young son Aegon Targaryen, and removing the Lady Stoneheart storyline to changing Tyrion’s real motivation for killing Tywin Lannister, Game of Thrones’ adaptation neglected some of the most important revelations from the books.

The season 4 finale of Game of Thrones sees Tyrion kill his father Tywin, who had been cruel to him his entire life. After Tywin sentenced his own son Tyrion to death for killing Cersei and Jaime’s son Joffrey Baratheon, even though he knew it wasn’t true, Jaime helped Tyrion escape the dungeons and flee to Essos. After being freed, he found his way up to his father’s chambers, where Tyrion found his girlfriend Shae in Tywin’s bed. When Shae lunges at him with a knife, Tyrion tearfully chokes her to death before taking a crossbow and pointing it at his father, who sits on the privy. By the end of their conversation, Tyrion fatally shoots Tywin twice with a crossbow before being smuggled out of King’s Landing, where he would soon become an ally to Daenerys Targaryen.

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The circumstances under which Tyrion kills Tywin in George R.R. Martin’s A Song of Ice and Fire books are similar, but there are a few key differences that entirely change why Tyrion decided to murder him. Considering GRRM stopped writing episodes after Game of Thrones season 4, which is when the series began diverting heavily from the source material, the reason why the show changed the motivation for Tyrion’s patricide seems to be more heavily based on the aftermath of the event. Here’s a breakdown of how Game of Thrones changed Tyrion’s reason for killing Tywin, and why the series went in this direction.

Why Tyrion Killed Tywin In GOT Season 4

While the idea of Tyrion killing Tywin wasn’t surprising, the actual act of him pulling the trigger was a major twist at the end of Game of Thrones season 4. The reason why Tyrion decided to kill Tywin in Game of Thrones was an act of revenge for himself. Throughout his entire life, Tywin had treated Tyrion like a “bastard” due to his dwarfism and the wrongful assertion that he killed his mother, who had died giving birth to him. Tyrion was treated horribly by everyone in the historic House Lannister aside from Jaime, but still had a tiny sliver of hope that Tywin harbored some genuine love for him as his father. Once Tyrion discovered that Tywin was prepared to execute him for killing Joffrey, which Tywin knew that he didn’t do, Tyrion realized that he truly never loved him. Paired with the fact that Tywin was sleeping with Shae, who Tyrion loved and Tywin threatened to banish, the extent of Tywin’s cruelty was realized in his son’s eyes. It was inevitable that Tyrion would pull the trigger on the crossbow in Game of Thrones, but it wasn’t until Tywin called Shae a “whore” again after Tyrion repeatedly told him not to that he killed him. Lannisters keep their word, so there was no way Tyrion was going to let Tywin live after he had already promised that word would signal his death.

While Shae’s betrayal and the Lannister lord then calling her “whore” was a catalyst for Tywin's Game of Thrones death, it wasn’t the primary reason why Tyrion wanted to kill his father. Tyrion killing Tywin in Game of Thrones was based on getting revenge for all the cruelty from Tywin on himself throughout his life, with the reason for pulling the trigger being fueled by anger for himself. This is completely different from why Tyrion kills Tywin in the books, which is fueled by his anger and need to get revenge for Tysha, Tyrion’s first wife. While Tysha was mentioned in passing a few times in Game of Thrones, her true backstory is never revealed in the series, and it’s only once Jaime tells Tyrion the truth about her that he decides Tywin must die. In Game of Thrones, Tyrion kills Tywin as justice for himself; in George R.R. Martin's books, Tyrion kills Tywin as justice for Tysha.

Tysha’s Real Game Of Thrones Backstory Explained

Jaime visits Tyrion in his cell in Game of Thrones

In both the books and Game of Thrones’ show, Tyrion meets Tysha as a teenager, finding her on the road as she escapes an attempted rape. Jaime fended off Tysha’s attackers, whereafter Tyrion helped Tysha recover and they soon married. Tyrion and Tysha were only husband and wife for two weeks before Tywin discovered their marriage. Angry that Tyrion would marry a commoner, Tywin cruelly ordered the Lannister guards to gang-rape Tysha as Tyrion watched, with Tywin paying her silver for each man. Tyrion explains in Game of Thrones season 1 that Jaime eventually told him Tysha was actually a prostitute, so he organized the entire charade of the attackers so that Tyrion would finally lose his virginity. Jaime claimed not to know that Tyrion would marry her or what Tywin would do in response, but his marriage would soon be annulled with the assault being the last time Tyrion saw her.

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This is where Game of Thrones diverts significantly from GRRM’s books. While Tyrion believed this story about Tysha actually being a prostitute for most of his life, Jaime finally confesses the truth about her when he visits Tyrion in the dungeons after he was sentenced to death. Jaime explains that Tysha was never actually a prostitute, she was just a common girl who genuinely did love Tyrion when he married her - the entire event in which they found her fighting off would-be assaulters was true. Game of Thrones' conniving Tywin had forced Jaime to tell Tyrion that Tysha was a “whore” and everything was a charade, hoping Tyrion would never return to her. Another major detail that Game of Thrones omits in Tysha’s backstory is that Tywin forced Tyrion to rape Tysha last after every guard had already done so, with Tywin paying her gold because he’s a Lannister. In Game of Thrones, Jaime never reveals the truth about Tysha, so Tyrion’s fury with Tywin after Jaime helps him escape is simply about his own relationship with Tywin.

Fueled by incredible rage after hearing the truth, Tyrion strikes Jaime, tells him about all of the men Cersei has slept with while he was gone, and falsely confesses to Joffrey's murder (Olenna Tyrell was really responsible) before leaving the dungeon with the intent to find Tywin. Tyrion finds Shae in Tywin’s bed and kills her before pointing the crossbow at Tywin on the privy, this time asking him about Tysha rather than Shae. Like with Shae, Tyrion tells Tywin that if he calls Tysha a “whore" again, he’ll kill him. Tywin tells Tyrion that he never killed Tysha, but says she went “wherever whores go,” so Tyrion keeps his promise and kills his father. Tyrion’s motivation for killing Tywin in Game of Thrones is completely different and sends him on an entirely new trajectory - so why did Benioff and Weiss change such an important detail?

Why GOT Changed Tyrion’s Motive For Killing Tywin

Tyrion holds a crossbow in Game of Thrones

At SDCC 2014, showrunners Benioff and Weiss revealed that they omitted Tysha in Tyrion’s reason for killing Tywin because there wasn’t enough time to fit in every book subplot, but this feels like a fairly weak excuse. When considering how differently Tyrion’s future after killing Tywin was in the books compared to Game of Thrones, it seems the series wanted to maintain a certain level of justice for Tyrion himself that would better send him into an allyship with Daenerys Targaryen. In the books, Tyrion is sent into a deep depression after killing Tywin and discovering the truth about Tysha, which admittedly isn’t as exciting a plot for Game of Thrones season 5 than his journey to being taken to Dany. Tyrion’s discovery of Tysha’s real background is harder to be expressed onscreen than in the books, plus revealing this truth likely would have required a flashback scene, which Game of Thrones largely strayed from. Since readers are inside Tyrion’s head, it’s much easier and more powerful to convey this reason for his final decision to pull the trigger on his father.

In Game of Thrones’ books, this was also the moment that destroyed Jaime and Tyrion’s relationship, and the show was focused on maintaining their brotherly bond and a source of redemption for both characters. It’s also possible that Game of Thrones decided to leave out Tysha’s story as a source for Tyrion killing Tywin because her background was far less important to his character in the show than in the books. She was also only given a prominent scene for her background back at the time of Game of Thrones season 1, so many viewers likely wouldn’t remember the story well enough for it to be as convincing for why it would cause Tyrion to kill Tywin. As far as the books have gone, Tyrion is still hoping to be reunited with Tysha someday, whereas Game of Thrones’ changed his personal arc to focus on his relationship with Daenerys and his siblings.

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