It's a kind smile. It might be a lie (and even as she smiles back, open as if her city had never been bombed to ruin and her country invaded, she does not fully trust), but there is a kindness there.

Kindness and humour are things to be enjoyed, because they might not last. She's learned that lesson very well.

"Yes. But it is good to believe in. Friends. And...caring. Holmes and Watson cares about people, and helps them. It's nice."

The smile fades, like a ripple stilling on a pond.

"Am I allowed to sit?"