Of all the characters in Game of Thrones, the one who has had the most parabolic of arcs is Theon. He went from midrange ward of the Stark family to Ironborn conqueror of Winterfell. From that high, he then sank all the way to the bottom as Ramsay's torture pet Reek, completely erasing his own personality to survive. It was only when Sansa was threatened that he found himself again, and with the help of Yara, rebuilt his ego. Now he's looking for redemption in keeping Bran safe. Sadly, Theon dies saving Bran from the Night King in the third episode of Game of Thrones, but it was an exit to remember. Warning: Spoilers for Game of Thrones Season 8, episode 3 follow.
Theon knew from the beginning his task would be a thankless one. He was signing up for a suicide mission if the battle went badly. It's not like he could take down the Night King. (The looks on the faces of the other Ironborn when he volunteered said they knew it too.)
But even with a suicide mission, there's knowing you are willing to sacrifice yourself, and then there's the moment it actually comes. For Theon, that came late in the episode, as the rest of the Ironborn laid around him, felled by the Night King's army. Then the man himself strode in.
Theon wavered. Of course he did. The Night King is not just any man with a sword. He controls the Army of the Dead, and much like Bran at this point, he's otherworldly. A mere man could no take him down. No one could. (Well, OK, you get the point.) The point is, Theon is not the man to do the job, and yet, he was the only one standing between Bran and death.
Fans everywhere knew what was coming. Then Bran looked at him and told Theon he was a good man.
Theon screwed his courage to the sticking point, and threw himself at his quarry, knowing he could never actually do what he hoped to manage. At least the Night King didn't laugh at him for it. Instead, he did what everyone expected, taking down Theon nice and quickly, and one might even say, humanely.
It might not have been the end that Theon once dreamed of, back in Season 2 when he took Winterfell for his own. It might not even have been the end he'd hoped for when Yara dismissed him to go fight for the Starks one more time. But it was a heroic ending of sorts, and more importantly, it was one that cleansed Theon of his sins.
All those years ago, Theon stood in the Godswood and desecrated Winterfell, as Bran, Rickon, Hodor, and Osha made a break for it through the crypt tunnels, heading out on the journey that would ultimately lead Bran to become the Three-Eyed Raven. Theon may regret that choice now, but without it, it would not have made him into the person he was now, standing in the Godswood, defending Bran to his last breath. Everyone has a journey, and now Theon's has ended.