In the latest episode of “Game of Thrones” season 7, the reappearance of the Valyrian steel dagger used in the failed attempt to assassinate Bran Stark brought back into viewers consciousness one question that still remains to be definitely answered—who sent the assassin to kill Bran.
Littlefinger, in his usual manipulative and scheming self, gave Bran the dagger and even told him that it was the weapon used in the attempt to cut Bran’s throat.
Instead of being flustered by the revelation, a nonchalant Bran creeps out Petyr Baelish by quoting Littlefinger's motto in life, “chaos is a ladder.”
Bran later ominously handed over to Arya the rare and precious dagger as “its wasted on a cripple,“ he said. As if many-faced Arya needs another excuse to go over her list.
Bran may know who
If there is one person in Westeros who could answer with certainty this lingering mystery since “Game of Thrones” season 1, it is the Three-eyed raven or Bran himself. He actually hinted it to Arya and Sansa when he said, “Someone very wealthy wanted me dead.” The problem is, he is not telling anybody or maybe not yet.
But there were details in A Song of Fire and Ice novels that could reasonably deduce the identity of the one who ordered the assassination. That person was not your usual suspect and it was not ordered for the obvious reason.
Who did it?
Quick guess would be the incestuous twins, Cersei and Jaime, for they have a clear motive plus the fact that Jamie already tried to kill Bran by pushing him from the window. But in A Clash of Kings and A Storm of Swords, it was revealed that they were not responsible and that it may have been their bastard son, Joffrey, who did it in order to please King Robert Baratheon.
It was actually both brothers, Jaime Lannister and Tyrion Lannister, who assumed separately, based on circumstances, that Joffrey was responsible for the attempt on Bran Stark’s life.
Jamie Lannister’s theory
According to Game of Thrones Wiki, Jaime Lannister denied sending the assassin to kill Bran before Catelyn Stark, when he was her captive. Though he admitted that he pushed Bran from the window; and that both he and Cersei considered killing Bran when they learned he survived the fall.
In a later conversation with Cersei, Jaime recalled to his twin sister Catelyn’s accusation. Cersei then said that a drunk King Robert, talking about Bran’s condition, lamented that they kill horses when they break a leg; or dog when they go blind, yet they are too weak to give the same mercy when it comes to crippled children.
Asked by Jaime if Cersei and King Robert were alone at that moment, Cersei replied that the children were there as well.
Cersei then said that perhaps Myrcella sent the dagger but it was meant as a mockery. However, Jaime deduced that Joffrey could be responsible. He told Cersei that he was, “A child hungry for a pat on the head from that sot you let him believe was his father."
Tyrion Lannister’s assumed the same
During King Joffrey’s wedding, he made a remark about not being a stranger to Valyrian steel. This after he hacked Tyrion's gift with Widow’s wail; his new sword made from the Valyrian steel melted from Ice, the blade of House Stark.
Tyrion recalled that Joffrey was then jesting with the Hound about killing a wolf back in Winterfell. He discounted Jaime because he was too proud to outsource murder as well as Cersei because she was not stupid to use a weapon that can be traced back to her.
The dagger was actually owned by King Robert, who won it, in a bet, from Littlefinger. Petyr Baelish lied to Catelyn Stark about who owned the dagger; a lie that put into motion the war between the Starks and the Lannisters.
Joffrey may have found the dagger among King Robert’s stash of weapons and gave it to Bran Stark’s failed assassin.
All of these are circumstantial however and with Bran’s abilities, he may be the only one with the definitive answer.