Well.

Of course Lydia understood the backbone, as it were, of this ritual: sometimes you had to rip out your own heart for the magic to work. But that certainly was a box with a live human heart in it she'd held just then, and she was rather glad it was now safely buried because you shouldn't just hand your heart to people, Adrian! Didn't you know Lydia was terribly wicked? Just ask her sister Mary!

So Lydia was going through her own recuperative process over here, which involved sipping a cup of tea and mentally composing a letter to Miss Lambe.