Why do some people find themselves fixated on specific unsettling behaviors in their partners, like the "methodical smile" you described?

Why do people get such a kick out of pranking the coworker who's scared of something? Any memorable stories?
Why might some people struggle with the idea that they are responsible for their own negative experiences?
Is it hypocritical to hate narcissism if someone does it to you but be okay with it if they do it to someone else?