Also I must say: I do not like the way Collapse characterized John. Love his interactions with Joseph but I think characterizing his sadistic tendencies as some kind of struggle with violent impulses is actually pretty contradictory with what we are told in canon.
What John tells us in his bunker is "I spent my whole life looking for more things to say 'yes' to. I opened up every hole in my body and when those were filled, I created more. But it was Joseph who shower me how selfish I was being. Always receiving, always taking. The best gift isn't the one you get, its the one you give." That, to me, paints a pretty clear picture. As an outgrowth of his childhood abuse John spent his adulthood engaging in self-harming behaviors, seeking out scenarios where he could recreate that helplessneess and release as a way to feel cleansed. Its pretty clear to me that these habits were primarily self-destructive, even submissive in nature ("always receiving, always taking"). "Things to say yes to" isn't quite synonymous with the American Psycho kind of picture that Collapse paints, John seems to have specifically sought out scenarios where he would lack control, where he would be hurt and preyed upon. Until Joseph convinced him to instead enact those desires on others. Take everything that was done to you, and do it to other people, not only to cleanse them, but to finally save yourself from the sin inside you.
Like to be clear: this isn't me saying John wouldn't do malicious cruel things without Joseph's interference. But making him a knife-happy bad dominant stereotype with an obsession for strangling people both contradicts how the main canon tends to characterize him, and also imo whitewashes Joseph's manipulation. If John is a collection of violent impulses, Joseph becomes not one of his abusers, but his handler. Its kind of a consistent problem with the Collapse where it is wants to continually frame the actions of the siblings as what they probably would have done anyways. Joseph is wrong for gaining by it, but it shies away from pointing out where he not only encouraged it, but at times redirected it into specific, more beneficial channels.
John had his brother never showed up likely wouldn't have been a very good person! He would still be a corrupt lawyer deeply fixated on his own desires and with a very destructive personal theology. But he does not pick up the knife to use on others unless his big brother tells him to.
