Every problem of beginnings and backstories is multiplied a hundredfold in speculative fiction. In fantasy and SF, there’s so much more that the reader needs to be told—not just the backstory to the characters, but the backstory to the whole world.
Think of a realistic novel. We’re aware that the characters and main events are made up; quite likely, the street where the characters live is made up too; and possibly even the suburb. But spreading further afield, we eventually reach the bedrock of our own real world. San Francisco is still San Francisco, with its hills and bay; Union Square is still Union Square; the Barack Obama on the characters’ TV screens is the same Barack Obama as on our TV screens; and the Taliban they read about is the real-world Taliban we read about.
These things are all real in the sense that we can expect our real-world knowledge to apply to them. We’re not going to find Union Square inhabited by dinosaurs or the Taliban as a group of neo-Marxist socialists.
With speculative fiction, our thinking runs the other way. If these particular characters live under such different conditions, then the whole world must be fundamentally different. We can’t rely on any of our normal assumptions about history or geography. Things will keep on being unfamiliar however far we look.
For anyone who loves speculative fiction, this is one of its special delights: the fascination of what’s possible on the borders, or beyond the borders, of the novel.
The Lord of the Rings is the first best example. Our imaginations play with the glimpsed wonders of the past (exactly what happened with Thangorodrim and Angband?), or the glimpsed realms in Middle Earth that Tolkien didn’t describe (the Easterlings and the realms around the Sea of Rh^um?).
(I won’t get into the argument on whether the answers provided in The Silmarillion lived up to the suggestions in LOTR … enough that we were desperate to learn more!)
However, the special delight is also a special curse. The great danger for all speculative fiction is ‘info-dumping’, when the writer shovels huge undigested loads of background material onto the reader. It’s so tempting to let the forward story disappear while explaining the different history and geography and general conditions of this world for pages at a time.
If balancing backstory and forward story is a juggling act in all genre fiction, then in speculative fiction it’s the juggling act supreme.