Ephraim had been impressed by many times before by Darcy's strength and resilience, and her sister was similar in many ways. She was more brief and to the point. Stoic in many ways. He was glad to see that she was a sister Darcy could rely on. Not meek or frail.
She was very good at hiding what she felt. He could tell from the moment he gave her his handkerchief that it was a mistake. He had already smelled her scent and he was still struggling with this new knowledge. He should have expected something, knowing that they are twins. The fact that she was at the end of her fertile days, didn't help block the scent at all and it was highly disturbing.