Ella was alone with Cleopatra, and she noticed her sister's demeanor had changed despite Cleopatra's best attempts to hide it. She led her into a room that their parents had kept off-limits to them as kids. They weren't allowed anywhere near it, so it wasn't an exaggeration to say that Ella had never been in it. This was because she left the house at an early age and had never been considered part of the family. Naturally, they allowed Cleopatra in once they deemed her old enough to handle herself in such a situation.
She was the heir to everything they had worked so hard in life for but it was a pity that they didn't live long enough to see Cleopatra extend their bloodline with a husband and a child.