Join the organization.
It had been Zaen's goal from the moment Hina told him about it. However, he didn't think the opportunity would arise so soon.
As for Zoey, she mistook Zaen's silence for reluctance. Perhaps the organization didn't hold much value in his eyes.
Wait, that might be insensitive to say in his case.
Jokes apart, Zoey couldn't really blame Zaen for being hesitant. Unlike most survivors, he didn't look scared of anomalies. If he was, he wouldn't go out of his way to hunt them in the real world.
From her angle, his reluctance seemed to stem from his encounter with the organization. Not only did they fail to save him in time, but they even held him hostage in the mental institute, though the latter part was unavoidable given the circumstances.
Still, the organization had failed him multiple times, and now he was being asked to join them.
If that didn't work, then there was always another method.
Coercion.
