Maybe it's the Broly/Goku scenario? They were both trained at the age of 6(like Broly suffered through Goku as toddlers) and Locke hated John because he was always superior. When Locke gets asked to bring back John and sees him already injured, he has the temptation to kill him? [spoiler]Or Chief has Mangekyou Sharingan and tricks Locke into believing he is the one presiding over Chief. Plot twist[/spoiler]