If it helps, Elizabeth doesn't seem to care that she isn't appearing casual.

"Have an older sister and a younger brother. It was just the three of us mostly."

She then stops, had Theodore met her sister's guests? It was possible. It was also possible he was just sulking in the room because his ordeal ended just as badly as Elizabeth's and it just ended as opposed to another happening.

"Margaret is the strongest, she trained us though... Theodore spent more time with his building projects and I prefered more physical things. Would you like someone to what is the word.... See? No... Point? No... Notice! For you while you train?"