She agrees

Arya had always wanted to fight. She was born a fighter, always brawling with her siblings and friends. She was trained to be a fighter by the First Sword of Braavos, Syrio Forel. She was taught the value of anonymity by Yoren, a brother of the Night's Watch. She was taught the value of a life by the faceless man Jaqen H'ghar. And, above all, she was taught how to kill by her companion, friend, and hated enemy, The Hound, Sandor Clegane.

"I'll do it," Arya said, trying to appear strong. Melisandre just smiled, knowing she had achieved victory.

"Very good," the red woman purred, standing up. Her red robes flowed behind her as she approached the Stark girl. Wordlessly she circled her, like a merchant appraising a cart or a horse. After almost a minute of this, Melisandre began walking away. Still stunned, Arya stayed rooted, frozen in surprise and curiosity.

"Feel free to follow me when you're ready,"Melisandre chuckled, laughing as Arya rushed to catch up. "You may have chosen correctly, but before you can join us you must be initiated."

"What does that mean?" Arya asked, puzzled and worried. She had heard stories of the red woman's cruelty, and feared the worst.

"You will learn soon enough," the older woman replied, leading Arya deeper into the Red Keep.