"It was too late," Draven thought as his eyes met hers. He was in his beastly form, his eyes red like a hawk ready to pounce on his prey, his fangs standing out sharply. At this moment, he appeared as a nightmare to any human—one that parents may warn their children about. Today, what he had feared the most had come to pass; she now knew who he truly was and the danger he posed to her.
Earlier, when Draven had sensed Madeline's scent nearby while he was still held in chains, his senses became heightened to an extreme degree. This intense sensitivity caused him to struggle with controlling his emotions and impulses.
The rage building inside him at his own weakness before her led him to fight against the chains holding him back. However, that may have been a poor decision. He could have perhaps escaped after freeing himself before she saw him, but now it was too late; she had already seen him.