Zuko looked down, holding the mask in both of his hands so that he could peer into the lifeless black eyes surrounded by blue and white paint. She was basically telling him what his uncle had told him before in Ba Sing Se, after he'd freed Appa. Iroh would be highly disappointed in his nephew for even contemplating putting it back on. And if he were to put the mask away, to stop pretending like he was still on Azula's side out of a need to bring back the close relationship he had with his sister when they were younger (something that would never, ever be fixed...even he knew that), and actually act like the real Zuko...he knew that Iroh would be proud of him, for that was the sort of man Iroh wanted him to be.
The sort of person he wanted to be.
Looking up at her, Zuko nodded, and held the mask out to her. "You keep it."