Judging from his reaction, that wasn't information anyone had shared with him before. He wanted to disbelieve it... but why would Cho lie? Especially after admitting to having regained so much of his memory himself?

"That doesn't make any sense," he muttered, kneading the tension out of the back of his neck with one hand. "They're just memories. Why should it matter if we remember our lives or not?" Folding his arms again, he stared up at the ceiling, as though expecting that the answer would fall from the sky. "Why don't they want us to remember?" He drummed blight-stained fingertips against his bicep. "What don't they want us to remember?"