There wasn't even much of a flinch at the confession to being a serial killer, although his age made it more of a surprise. The youngest UnSub they ever had to deal with during his time in the BAU had only been nine, but although Helix is almost twice that he's still well below the average. It explains some things, puts his early assessment into perspective. Tidies up the profile.
"Why would I do that?" he replied. "That's not the way it works. The reason why profilers gather so much personal information is so that we can understand the suspect and anticipate his or her movements, but you're not a suspect. We're just talking and I didn't come to you as a member of the Force, I came to you on my own initiative. It wasn't sanctioned by the Defense Force, and unless you give me a really good reason to give this information to them it'll stay between the two of us."
A small pause and a steady gaze, his voice gaining some more gravitas.