on Writers Helping Writers:

Some characters are so dynamic, we feel immediately close to them. Everything they say, do, and think is consistent with who they are, they have a past and present, and as we share their experiences, we never have to guess at what they feel, want, or need.

This authenticity happens when the author does the deep work to understand the character inside and out. And, I’m betting they did something else, too: created a reference file about the character, a.k.a., a Character Bible. This is a great way to avoid unintentional inconsistencies and mistakes.

And mistakes do happen, because we forget things —Does Emma fear lizards or birds?—or we change our mind mid-book, and the love interest, Liam, goes from being a skateboarder to the king of parkour. Oh, and name changes? Don’t even get me started!

The point is that nothing pulls readers out of the story faster than when details shift, so implementing a way to keep each character straight in our minds is key.