_______ killed the cat, but it was the wonder . . .

Curiosity.
He has always been very interested in things. How they work, why does X happen. One day last winter John found himself on the verge of explaining how gravity works and saved himself by saying, "Hey look Christmas lights!" (there really were Christmas lights). That has since been our exclamation when things are getting dangerously close to the way too complex for both of us at this very moment.
Example:
Operation underwear is well underway and going rather well.
Today I was waiting for him to pull up his pants and wash his hands when I heard the toilet flush, again. No, I was not worried about inappropriate items taking a dip, but I was right to be worried about something.
After knocking on the door and entering briskly, I found Odin, standing by the toilet, pants still around ankles, with the very ends of his bangs wet. Big water droplets on his bangs. When I asked him what he was doing he simply replied, "What."
I then asked if he was trying to figure out how the toilet worked, he said "yes." Fast forward to us watching a video of how toilets work online.

I know the curiosity is an asset, but sometimes. . . . ewwwwwwww.