The single most important technique for making believable characters...is to give them choices and let them make decisions.

The first rule of writing is, 'If you want to write, write.'

Science fiction is the literature of 'what if?' What if time travel were possible? What if we could live forever? What if aliens landed on Earth?

Character is built by making choices and decisions.

Story is the vehicle we use to make sense of our lives in a complex world.

Worlds of Wonder: How to Write Science Fiction & Fantasy