Arya Stark, the First Avenger
As they continue their travels, Arya and the Hound discover a group of Frey soldiers camped along their path. They overhear the four men mock her mother's death and delight in descriptions of her brother's mutilated corpse. Arya slowly dismounts from the horse she shares with her pseudo captor and offers the men money for food, showing one of them a Braavosi coin as collateral. When the man reaches for payment, she drops the coin and stabs him in the back several times. The other men react, but the Hound strikes them down. After the fight, he asks her if this is the first time she's intentionally killed a man, and she confirms. The moment is brief, but a bond is formed as it's clear that they will fight for each other when necessary.