He understood Sterling was being friendly because he appreciated Verity Calliwell, a young, promising witch with medical talent.
Sterling probably did not think much of their interaction and thought Verity was merely interested in his lab. However, Callum could see that the woman was not interested in just the opportunity to learn medicine from Dr Morgan.
He could see the part of her that was eyeing Sterling like prey. Like Callum, she was a predator, even though a pretty face, a beautiful smile and an elegant dress could hide her nature.
She was a different kind of hunter. Instead of choosing aggression, she was lulling Sterling into a false sense of security. Once Sterling accepted her into his lab, it would be a matter of time before she trapped him.
