Blake's jaw dropped at Lily's slip. Ever since the day of the kidnapping, Blake had been worried that his biological father Josh was involved. Of course he had no real evidence to conclude that Josh was indeed a Death Eater, but he could not help but suspect anyway. And now he was standing here wondering whether he was the only one who suspected this.
Wait, what if that's not what she meant? Blake thought, desperate to try to maintain some form of composure. After a moment of self debating, he finally came to a conclusion that either way, he needed to tell someone, and who better to be that someone than Lily?
"Hey Lily," Blake interrupted, "I need to talk to you about something after... maybe when you're done with detention?"