He makes a thoughtful sound, considering what Nick says for a moment... Tonic hasn't been a doctor for very long, but he was something before that to which the statement still might apply. He wonders if he used to care more, when people died. If he'd ever had the thought to find out what happened to them. The thought of then giving that information to the people they left behind, though, that makes his stomach churn just imagining it.

"Oh." He says, suddenly, "Because it needs to stay a secret."

He glances up a second later, realizing with surprise that yes, he definitely said that out-loud. "Sorry, that was... I think I just found a piece of it."