Hello to all, I am new and honored to be among this company.
In Chapter 32 (pp.345-361) of his book, Kolar discusses a videotaped interview of BR conducted on January 28, 1997 by Dr. Susanne Bernhard as part of a required Department of Social Services protocol. Bernhard found BR unattached emotionally to his family, as evidenced by (among many other indications) a drawing he did depicting himself as larger than his mother. JBR was entirely absent from the drawing. JR was shown as a figure in the cockpit of a plane, removed from PR and BR. The psychologist interpreted this to mean that BR saw Patsy as insignificant in relation to himself, and his father as a remote, functionally ineffective figure; only weeks after her death, JonBenet does not even register as a member of the family.
My sense is that the abuse suffered by BR would have involved feeling disenfranchised as his parents focused most of their attention on JBR. I suspect that BR harbored a great deal of rage, acting out in ways that the parents would have sought to keep private.
If BDI, I believe that a feeling of emotional isolation, peripheral importance within the family unit, and subsequent anger might have led to a fatal explosion directed against his sister - and that prior, smaller-scale events could have characterized their relationship from the outset. Parental staging of the crime scene and fierce protection of BR at every stage of the investigation would have been as much the expression of guilt and realization too late, as acts of personal face-saving. (Just my opinion.)