No, Tywin Lannister did not know that Arya was a girl.
The Unsuspecting Lord of Casterly Rock
During his occupation of Harrenhal, Lord Tywin Lannister, one of the most formidable and cunning strategists in Westeros, remained completely unaware of the true identity of his young cupbearer. Arya Stark, daughter of the executed Lord Eddard Stark and sister to Robb Stark, the King in the North, was disguised as a commoner, first as "Arry" and later as "Nan" or "Weasel" at Harrenhal. Her disguise was so effective that even Tywin, despite his keen intellect and sharp observations, never suspected her gender or her noble lineage.
This critical oversight highlights the effectiveness of Arya's concealment and the unexpected nature of her presence in such a high-stakes environment. She blended seamlessly into the background of servants, allowing her to move relatively unnoticed and even engage in surprisingly candid conversations with Tywin himself.
A Missed Strategic Opportunity
Tywin Lannister unknowingly recruited Arya Stark into his service as a cupbearer. This represented a significant, though unrecognized, strategic blunder and a colossal missed opportunity for the Lannister war effort. Had Tywin known her true identity, Arya Stark would have been invaluable leverage in his war against Robb Stark.
Consider the potential ramifications:
- Hostage Negotiation: Arya's capture would have provided Tywin with a powerful bargaining chip against Robb Stark, potentially forcing concessions or even an end to the Northern rebellion.
- Political Pressure: Her existence as a Lannister prisoner could have been used to destabilize the Northern alliance and sow discord among Robb's bannermen.
- Information Gathering: With her identity revealed, Tywin could have interrogated her for information about Robb's strategies and movements, though Arya's knowledge might have been limited.
The fact that Tywin unknowingly had the daughter of his primary enemy within his grasp, serving him directly, underscores the ironic nature of their interactions at Harrenhal.
The Dynamics at Harrenhal
The scenes between Tywin and Arya at Harrenhal are some of the most compelling in the series, precisely because of this hidden truth. Tywin, always perceptive, recognized Arya's intelligence and spirit, often engaging her in discussions about history, politics, and the state of the war. He saw her as an unusually bright commoner, but never as the highborn lady she truly was. This dynamic allowed for fascinating exchanges where Arya, despite her fear, managed to glean information and even subtly manipulate situations, all while under the nose of her family's greatest enemy.
