From The Grey House:
Vincent sounded amused. He knew what Natalia was doing but wasn’t sure he agreed with her actions. She had said several times that she was going back to Zechariah, and Vincent hadn’t given it much thought. He joked about it but dismissed it out of hand. He wasn’t letting her go anywhere but was starting to appreciate the level of her loyalty to her possibly captured friend. As she took another blow to the face, faked a punch and took another hit, he began to understand her and respect the depth of her loyalty.