Kestrel had always believed that Ren was an exceptional alpha. One of the main reasons was that he had been able to keep his emotions hidden in front of her. That was a skill not many possessed. Even for powerful alphas, it wasn't common.
Usually, Kestrel's tendrils could pick up on the emotions floating around her. For example, she knew Priscilla had been feeling blue that day, Locky had been on cloud nine, and some young apple vendor had secretly desired one of his apples. But with Ren, her ability often hit a brick wall.
Ren had this solid psychic barrier. He had mastered the art of controlling what he let out, concealing himself so well that Kestrel's tendrils once mistook him for an emotionless stone.