Theon Greyjoy, played by Alfie Allen, is the last remaining son of Balon Greyjoy, and brother to Yara Greyjoy.

Early Life

Theon was born in Pyke, heir to Balon Greyjoy, the Lord of the Iron Islands. In his childhood, his father launched a rebellion against the Iron Throne, and was defeated. As punishment, Balon was forced to send his last surviving son, Theon, to Winterfell as a ward and hostage.

At Winterfell, Theon was raised by Eddard Stark, and despite his father's actions, was treated well and grew up alongside the Stark children. Theon grew close to the eldest son Robb Stark, with whom he was close in age, although Theon never felt truly at place among his adopted family.

The War of the Five Kings

During the War of the Five Kings, Robb Stark declares the north's independence from the Iron Throne, and leads an army to the Riverlands in retaliation for the execution of his father, Eddard. Theon joins Robb's campaign, and acts as one of his most trusted companions and advisers.

Following their victory at the Whispering Woods, Robb sends Theon to the Iron Islands to ask his father, Balon, to join the northern cause. Theon does so, but is surprised to find that his father has no interest in such an arrangement, and plans to create his own kingdom on the Iron Islands once again.

Torn between his loyalty to Robb, and his lineage as a Greyjoy, Theon chooses to betray his friend and brother, leading a group of Ironborn to Winterfell and sacking the castle.

Theon's plan soon spirals out of control though, and he is turned on by his own people and captured by Ramsay Snow.

Reek

At the Dreadofrt, Theon endures Ramsay's endless tortures, culminating in Theon's castration. Suffering a mental breakdown, Theon takes on the persona of "Reek," and serves as Ramsay's personal lackey.

Theon continues to serve Ramsay for months, joining him in Winterfell after Ramsay's marriage to Sansa Stark. After witnessing Ramsay's continued abuse of her though, Theon has a change of heart and helps Sansa escape, leaving Winterfell with her. After Sansa reunites with Brienne of Tarth, who has pledged to protect her, Theon departs, leaving for the Iron Islands.

Reconciliation with Yara

After returning home, Theon reunites with his sister Yara, who is preparing to participate in the Kingsmoot, which will decide the next ruler of the Iron Islands. Theon pledges his support for his sister, stating that he no longer wants to rule.

Despite this, Yara is unsuccessful and their uncle Euron Greyjoy is declared king. Yara, Theon, and their supporters flee the Iron Islands, stealing many of the Iron Fleet's best ships in the process.

Theon joins Yara as she travels east to Essos, planning to forge an alliance with Daenerys Targaryen. Arriving in Meereen, Yara pledges her loyalty to Daenerys, on the promise that she allow the Iron Islands to remain independent.

Return to Westeros

Theon accompanies Yara's fleet back to Westeros, ferrying Daenerys Targaryen's army to Dragonstone. Once there, he participates in Daenerys's plan to lay siege to King's Landing using forces from Dorne, and remains aboard Yara's command vessel as they travel south.

En route though, they are ambushed by Euron's Iron Fleet, and almost all of Yara's ships are destroyed. Yara herself is defeated and captured by Euron, and in a moment of cowardice, Theon jumps overboard rather than face his uncle.

Theon is rescued from the sea by one of the surviving crew members of Yara's fleet, and returns to Dragonstone. He is reunited with Jon Snow, who tells him that what Theon did for Sansa is the only reason that Jon is not killing him.

Theon and Jon later reconcile, with Jon forgiving him for what he did to the Stark family. With newfound confidence, Theon returns to the ironborn survivors and declares that he will lead a rescue attempt to bring back Yara.

He is initially mocked by Yara's men, but after killing their ringleader in a hand-to-hand fight, he earns their respect. He is last seen washing the blood from his face in the sea, as his new crew prepares the boats to depart.