How do screenwriters create characters for action, sci-fi, and fantasy worlds?

How do screenwriters create characters for action, sci-fi, and fantasy worlds? Heard at a session with Marc Bernardin, Naren Shankar, and Emily Carmichael about building worlds at the ScreenCraft Writers Summit 2021

Well-written characters attract audiences.

Game of Thrones is fantasy world but never makes the fantasy elements too derivative.

The Expanse characters reflected a blend of the historical War of Roses and Lord of the Rings.

Character is important on TV. Serial nature of TV shows character development.

Start with emotional events like climax, and then go to character after thinking through emotional underlayers. 

It's not a show until you start talking about people. World is only important based on what character can see, so don't go overboard with setting.