There's a curious quirk with the human brain. It's how it's possible to navigate the social context without our heads melting.
Because think about it: in order to do just about anything, you need to predict how other people react.
But you can't simulate another brain (and maintain your own) without being orders of magnitude smarter than they are.
Somehow, you manage. Sure, it's not perfect, but you can usually predict how people will respond.
When to use flattery and when to be stern, for example.
This quirk of your unconscious mind can let you learn insights from people you've never even met.
Even people you could never meet.
The funny thing is that it even works with fictional characters.