Yes it’s hard to wrap ones head around. It’s actually what happens in narcissistic households. The narcissist (Emma) runs the show and chooses someone to take all the blame. The rest of the family is afraid of the narcissist so they go along with whatever they want. It’s a special kind of hell for the scape goat. In this particular family, it resulted in murder.I cannot get my head around this either? It’s like a pack mentality but against a child? The only thing these two seemed to bond over was how awful Arthur was and how they were going to punish him. It seems like their entire relationship was purely derived from taking pleasure from torturing that child - psychologically, emotionally, verbally and physically.