Once you have a landscape filled with exotic creatures, towns and cities, governments and religion, it’s time to think about how all these things come together to influence the characters and the story you want to tell.
It’s one thing to create a cool critter, but when it becomes a symbol of a certain religion, or perhaps part of a legendary stampede that flattened a whole town, then your cool critter becomes part of a wider story that can be worked into your character’s journey through a conversation or perhaps a mural on the wall.
For every creature, or plant, or feature of the landscape you’ve painstakingly designed, take a moment to note down a little story in which this thing plays a leading role. In my world, for example, my friend Max and I created the gallows worm, a creature which hangs from trees in the Black Forest and captures unwary animals, pulling them up by the neck into the branches and devouring them from the inside out – leaving horrific ’empty’ shells (which obviously give the Black Forest its reputation for being a scary, haunted place). I went one step further, though, to give a terrifying run-in with a gallows worm to one of my adult characters when he was a young man. Some of these things will never make it onto the pages of your book (at least, not as central plot points), but having things to mention in passing makes the world feel so much bigger and cooler!
So go crazy. Perhaps your character had one of your new critters as a pet growing up, or maybe their mother was addicted to that plant you made up during her pregnancy… (What were the effects on the baby?!?!)
The same idea applies to towns, governments and religion. Perhaps your character’s grandfather came from that town. What was it like for him, growing up there? Was there enough food? Were the rulers kind, or unforgiving. Perhaps he might have lost his first wife to a famine and chose to leave – to begin again in your characters’ home town.
Anything goes, and you’ll quickly see the benefits of relating your inventions to your characters.
We live our lives in a world saturated with stories. The tales told to us by our parents about their lives, their parents and their beliefs help define our identity (whether we identify with them or rebel). The parables told by religion shape everything from morality to social norms. Even the gossip is a little story told by one person about another who has been sufficiently interesting as to warrant the attention.
Ultimately, you are probably building this world of yours to act as a backdrop against which you tell your epic story. If you take the time to record plenty of little stories, myths and anecdotes, your world will have a sense of depth and history which will, I promise, make writing the ‘real story’ quite exciting.