Trial of Petyr Baelish

"You stand accused of murder. You stand accused of treason. How do you answer these charges... Lord Baelish?"

- Sansa Stark

The Trial of Petyr Baelish is held in the great hall of Winterfell by Lady of Winterfell Sansa Stark, with Arya Stark and Bran Stark, against Petyr Baelish, the nominal Lord of Harrenhal and the Lord Protector of the Vale. It is witnessed by Lord Yohn Royce and multiple Stark and Arryn men.

Prelude
Sansa and Baelish talk about Jon Snow and Daenerys Targaryen forming an alliance, with Baelish suggesting that Jon should be unnamed as King in the North.

Sansa knows that Arya would not tolerate it and that she is now a killer, having trained with the Faceless Men, whom Baelish only knows by reputation. Baelish explains that when he wants to understand a person's motive, he plays 'a little game' and plants the seed that Arya wants Sansa dead for apparently betraying their family and to replace her as Lady of Winterfell.

Trial
Sansa has Arya brought to the great hall in front of the lords of the North and the Vale. Addressing Arya, Sansa states her desire to protect the North and House Stark. She then proceeds to state the accusations of murder and treason, asking how these charges are answered. Because she continues to look at Arya, it appears she is directing her question to her sister, but Sansa then adds, "Lord Baelish", revealing it is he who stands truly accused.

Taken by surprise, Baelish tells Sansa he's confused. Sansa starts with the simplest charge: that Baelish murdered their aunt Lysa Arryn by pushing her through the Moon Door and asks if he denies it. Because Sansa herself was a witness to Lysa's murder, Baelish admits to it but claims he did it to protect Sansa. She refutes his claim by making her own: he did it to gain control of the Vale.

The next charge laid against Petyr is that he orchestrated the murder of Jon Arryn by giving Lysa Tears of Lys, which she used to poison him. Asked whether he denies this charge as well, Baelish avoids a direct response by explaining that Lysa's state of mind made her see enemies everywhere, implying that Lysa acted alone.

Sansa accuses Baelish of having her aunt send a letter to Lord Eddard and Lady Catelyn Stark, claiming the Lannisters murdered Jon Arryn. The result of the letter set events into motion that started a feud between House Stark and House Lannister, eventually culminating in the War of the Five Kings. This accusation, if true, would make Baelish the true instigator of the war. This time, Petyr directly denies knowledge of the letter.

The final charge is that Baelish conspired with Cersei Lannister and Joffrey Baratheon to betray their father, Ned Stark, which led to his imprisonment and, ultimately, his execution on false charges of treason. Now clearly angry, Sansa asks Petyr if he denies it. Baelish directly states, "I deny it", stating that none of them saw what happened, and thus there is no case against him. However, Bran, having seen Baelish's crimes through his powers in Greensight, says that Baelish held a knife to Ned's throat and repeats what he told Ned when he betrayed him: "I did warn you not to trust me."

Arya says that Baelish told Catelyn that the Valyrian steel dagger that an assassin used to try and kill Bran belonged to Tyrion Lannister, which was another of his many lies: the dagger, in fact, belonged to Baelish.

With the court against him, Baelish pleads that he has known Sansa since she was a child and that he's always protected her, to which Sansa retorts that he sold her to the Boltons. When Baelish asks if they can speak alone (presumably where he believed he could manipulate Sansa into freeing or even exonerating him), Sansa repeats his words of 'playing a little game' to assume the worst of someone, thus assuming the worst reason Baelish has for turning Sansa and Arya against each other, deducing he did the same to Catelyn and Lysa. Baelish protests, demanding a chance to defend himself, but is ignored.

As Baelish realizes he won't be able to talk his way out of this, he commands Yohn Royce to escort him back to the Eyrie as the Lord Protector of the Vale. Given the specific crimes Littlefinger committed against House Arryn, however, Yohn Royce no longer recognizes Baelish's authority, and thus refuses. Out of options and now terrified, Baelish pleads with Sansa for his life, confessing his love publicly for her and for Catelyn, though Sansa points out that despite this, he still betrayed both of them. Sansa sentences him to death and thanks Baelish for all his lessons, which she vows to never forget. As Baelish tries to speak one final time, Arya slits his throat with his own dagger. Sansa, Arya, Bran, and the Stark and Arryn men watch as the former Master of Coin bleeds out and slumps to the floor, finally dead.

Aftermath
With Petyr Baelish's death, House Baelish is rendered extinct, and all who died as a result of his ambition and deceit, including Jon and Lysa Arryn, Eddard Stark, and thousands of casualties from the War of the Five Kings, are avenged.