The sole subject about which BR showed signs of precociousness was the murder of his sister. Taking a toy to the funeral indicates that he felt a comforting attachment to his possessions. JB somehow impinged upon this security blanket?
The GJ indictments accused the parents of egregious criminal negligence. Conspiracy to commit murder was not its decision. Perhaps, a conspiracy charge should have been impossible to pursue at trial without involving BR, who was legally immune in CO?
While the author of the RN was desperately writing, the enormity of the night's extremely emotional events had to be flashing through their mind, both consciously and unconsciously. This author was still experiencing the murder and trying to process it. What had actually occurred would find its way up to the surface in some form. "Don't grow a brain, John!" could be a displacement, or a type of plea for JB to (re)grow her brain after the blow to the head? In other words: Grow a brain, Jon(Benet)! Likewise, the possibility of JB being beheaded looks back yearningly to the time when JB had a functioning head on her shoulders? (Of course, this all assumes that the RN was fabricated after the murder.)
"John" is posited by the RN as the one with the power to rectify the situation. In one way or another, the RN is demanding for JR to bring about a resolution, i.e., "It's up to you, John". Later, he will do this by 'discovering' the body, and contaminating the CS irrevocably.
