Whether you are writing two or twenty books that are connected to one another, story continuity is important. It provides consistency and smooth transitions for the reader. Readers will notice when a character has blue eyes in the first book and brown eyes in the fourth. Authors have enough on their plates without trying to remember every detail or spending copious amounts of time searching earlier books for answers.
In creating a series bible, I organize track and organize the details in each book into an easy-to-follow document. I also provide a short synopsis for each chapter, creating a concise and accurate timeline. The specific categories in the bible are up to the author, but they often include:
main character biographies
secondary character biographies
background character biographies
locations and settings
races, cultures, and societal norms
clothing and accessories
Biographies may include (but are not to limited to): full name, age, physical traits, birthday, parent and sibling names, location of birth, schooling, jobs, travels, friends, exes, hobbies, internal and external goals, secrets, goals, pet peeves, and any other backstory.
Since each bible is unique, they are completely customizable. It's truly about whatever is going to work best for the author.
20,000-40,000 words $150
40,000-60,000 words $250
60,000-80,000 words $350
80,000-100,000 words $450
100,000-120,000 words $550