Be careful: potential spoilers on "Game of Thrones" season 7 will follow! In the fourth episode of this season, "The Spoils of War," Littlefinger gives Bran the Valyrian steel dagger involved in Bran's assassination attempt back in season 1. Most fans think Bran's murder was ordered by Cersei or Littlefinger, but according to "A Song of Ice and Fire" book series, there is someone else behind the failed assassination attempt.
What Bran says in "The Spoils of War"
Keep in mind what Bran said in the last episode of the show: "Someone very wealthy wanted me dead." It's also worth noting that the young Stark openly asked Littlefinger about the dagger's owner. "Do you know who this belonged to?" he asked, and Littlefinger replied that he didn't know.
Who ordered the murder according to the books
The question is, who gave the Valyrian steel dagger to the killer? The answer is quite surprising. In the first book of George R.R. Martin's fantasy series, Littlefinger says that he had once owned the weapon, but he bet and lost it to Tyrion Lannister.
According to Baelish, Tyrion won the dagger when Ser Loras defeated his brother Jaime at the tourney on Prince Joffrey Baratheon's name day.
When Catelyn Stark captures Tyrion, he insists he never owned the ancient dagger. Please note that the War of the Five Kings started after Bran's assassination attempt: Littlefinger's lie contributed to triggering the war.
Let's get back to the dagger. When Jaime is imprisoned in Riverrun, he admits to Catelyn that he threw Bran out the tower window, but he swears that Tyrion would never have made a bet against him, therefore what Littlefinger said was a lie. Tyrion wasn't the one who owned the blade. Jaime also reveals Catelyn a very important detail: that dagger was displayed by Robert Baratheon during a feast.
King Robert was the man who won the bet against Littlefinger.
The story gets better
Obviously, King Robert would never have attempted to take Bran's life. Later in the books, Tyrion Lannister realizes that the man who hired the murderer should have been someone close to King Robert, someone rich and cruel, someone like Joffrey Baratheon. Tyrion thinks that Joffrey could have found the assassin in the camp followers attached to King Robert's party that reached Winterfell at the beginning of the story and that he could have grabbed the Valyrian steel dagger from his father's weapons stash.
Tyrion is not the only one to think that Joffrey could be the one who sent the killer. At a certain point in the books, Cersei recounts to Jaime what Robert Baratheon once said about Bran: "We kill our horses when they break a leg and our dogs when they go blind, but we are too weak to give the same mercy to crippled children." Since Joffrey was present when his "father" said this, Jaime realizes the young and cruel prince may have paid an assassin as a misguided attempt to impress King Robert.
This is the most popular theory about who ordered Bran's assassination. We must point out that we cannot be sure that the TV series will follow the books about this event, but Bran said "Someone very wealthy wanted me dead," and Prince Joffrey was very wealthy indeed.
What now?
We wouldn't be surprised if Bran, who can see "a lot of things now," would time travel to find out the truth about the dagger. In that case, he would probably discover how Littlefinger lied to Catelyn about Tyrion Lannister. But maybe Bran has something more important to think about, like the Night's King and his undead army, so this is just a hypothesis.