Lysa Arryn

"What wife would do the things I've done for you? What wife would trust you the way I trusted you? When you gave me those drops and told me to pour them into Jon's wine. My husband's wine. And you told me to write a letter to Cat telling her it was the Lannisters..."

- Lysa Arryn to Petyr Baelish

Lysa Arryn, née Tully, is a recurring character in the first and fourth seasons. She is played by guest star Kate Dickie and debuted in "The Wolf and the Lion." Lysa was the Lady Regent of the Vale, ruling on behalf of her young son Robin Arryn. She doted on her son and pursued a policy of isolationism since the death of her husband Jon Arryn. She presided over the trial of Tyrion Lannister for the murder of Jon Arryn and the attempted murder of Bran Stark. He proves his innocence in a trial by combat. Lysa refused to commit her forces to aid her sister Catelyn Stark in the War of the Five Kings. She meets her demise in the Season 4 episode "Mockingbird" after she is pushed through the Moon Door by her husband Petyr Baelish and falls to her death.

Background
Lysa was born into House Tully and was the second child of Lord Hoster Tully. She had an older sister, Catelyn and a younger brother, Edmure. Petyr Baelish was fostered with the Tullys and Lysa grew up with him.

Lysa married Jon Arryn during Robert's Rebellion. Lord Jon was the head of House Arryn and a leader of the rebel faction fighting to overthrow the Mad King. The rebels forged an alliance with House Tully through marriage, with Lord Eddard Stark married to Catelyn and the then-elderly Jon to the still young Lysa.

After the rebel victory in the war, Robert Baratheon became King and appointed Jon as his Hand. Jon served the realm well for many years as Hand of the King. Lysa and Jon have a single son, Robin Arryn. Lysa and Jon spent the next seventeen years in the capital of King's Landing, never returning to the Eyrie in the Vale of Arryn.

Jon died immediately prior to the events of the series, sparking King Robert's search for a replacement. Lysa fled King's Landing for the safety of the Eyrie with Robin, then six-years old. Robin is the titular Lord Paramount of the Vale. However, Lysa will rule as the Lady Regent of the Vale until Robin comes of age. She dotes on her son. She is considered mentally unstable by Tyrion Lannister.

Season 1
Lysa's husband Jon Arryn, the Hand of the King, dies of an apparent fever. Lysa flees the capital and returns to the Eyrie with her son Robin. She sends her sister Catelyn a letter claiming that the Lannisters murdered Jon Arryn for unknown reasons. This news convinces Catelyn's husband, Lord Eddard Stark, that he must accept King Robert's offer to become the new Hand so he may investigate further. During the king's visit to Winterfell Catelyn's own son Bran Stark is injured in suspicious circumstances.

Catelyn apprehends Tyrion Lannister on suspicion of trying to kill Bran. She brings him to the Eyrie to be questioned. Lysa is furious with Catelyn for exposing her to the wrath of House Lannister. She and Robin hold Tyrion in contempt, ignoring his threats that his house will repay them for any harm they visit upon him. Lysa orders Tyrion sent to Mord, the castle jailer. Tyrion and Catelyn are both disturbed by Lysa's excessive coddling of Robin, including still breast-feeding him despite him being several years too old for it.

Tyrion convinces Lysa to give him a trial, only to protest his innocence. He demands the right of trial by combat, supported by the mercenary Bronn. Bronn wins the battle, killing Lysa's champion, Ser Vardis Egen. Lysa reluctantly releases Tyrion.

Lysa receives a letter from King's Landing announcing that Robert has died and Eddard has been arrested as a traitor. She delays showing the letter to Catelyn, to Catelyn's annoyance. Catelyn asks that the knights of the Vale join House Tully and House Stark in fighting the Lannisters for his freedom, but Lysa refuses. Lysa insists that the Vale knights must remain at home to defend Robin. Catelyn leaves, frustrated and annoyed.

Season 4
Petyr Baelish, acting under his own promises to both Lysa and her niece Sansa Stark, arrives at the Vale, bringing Sansa to the Eyrie with him. Lysa greets Sansa enthusiastically, introducing her to her son Robin. She conveys her pity for Sansa's unfortunate marriage with the dwarf Tyrion Lannister, and asks if he ever forced himself on her, to which she replies "no". However, Sansa does not realize Lysa's boiling hatred for anyone associated with her sister Catelyn, whom she is still deeply jealous of, despite her murder during the events of the Red Wedding. Sexually eager, Lysa has her and Littlefinger wed immediately, promising to "scream" as he makes love to her. She admits to poisoning her own husband's wine and staging the Lannisters in his presence, using these actions as proof of her love for him. Lysa agrees not to refer to Sansa by her true name in the presence of anyone else, and has Robin show her around the castle. 

The following day, Lysa dotes over Sansa in petty conversation, and she shares her childhood memories about Catelyn. However, she begins to grow angry as she questions Sansa as to why Littlefinger cared so much for her, and if he ever forced himself onto her. Sansa is shocked, but refutes this, claiming that Lysa is hurting her, considering she is clenching her fingers tightly. Seeing Sansa is scared, Lysa returns to a naturing state, drawing her close, and comforting her.  Later, Lysa witnesses Littlefinger kissing Sansa in the courtyard, and goes mad with jealousy. She summons Sansa to the Great Hall, threatening to push her out the Moon Door to her death, but is interrupted by Petyr.

​Emotionally distraught and torn over Littlefinger's infatuation with Sansa, Lysa falls into a fit of tears, shoving her to the floor. Littlefinger feigns an apology, embracing her and promising her that he only ever loved one woman. To Lysa's shock, he utters "your sister", and then shoves Lysa through the Moon Door to her death, while Sansa watches.

In the books
In A Song of Ice and Fire, Lysa is Catelyn's sister, who is distrustful of the Lannisters. She dotes on her son excessively. In the books her son's name is "Robert Arryn", but this was changed for the TV series to avoid confusion with Robert Baratheon and Robb Stark. Lysa married Lord Jon Arryn to tie three of the Houses involved in Robert's Rebellion - the Starks, Tullys, and Arryns - more closely together. Given the large age difference between her and Jon, their marriage was not a happy one.

She is noted as overweight in the books, as a result of suffering two stillbirths and four miscarriages. The stress from these many pregnancies which ended in tragedy, combined with her distant relationship with her elderly husband, wore heavily on Lysa's mental state. This is also why she dotes so excessively on Sweetrobin, her only surviving child.

According to the TV series official pronunciation guide developed for the cast and crew, "Lysa Arryn" is pronounced "LIE-ssa AIR-in", as opposed to "Liss-ah".