Arya and Tywin, 'Careful now, girl. I enjoy you, but be careful'

Arya Stark becoming Tywin Lannister's cupbearer was a phenomenal non-book addition to the show, giving us one of the most compelling character dynamics in all of GoT. In this moment in S02E07, the two had a discourse about Aegon & his sisters who changed history. Subtly, they kept trying to outwit each other but the rapport and obvious respect between the two were never gone. And still, despite being fond of Arya, Tywin directly hinted that he sees behind the disguise she'd been putting up.