How does one start a novel working from a large amount of journal materials in order to create a biographical, fictional story?
Well, Stevie Nicks would write a song based upon her journal. And the Dixie Chicks song, Silent House, could have been written from journal entries. But. A whole novel? To my mind, it needs to have been one helluva life. But. Fictional? Why do you need the journal? And do you have any idea how much editing it took to remove a bottle of wine from the misspellings in this post?
If I understand correctly, you're talking about using a journal that you have kept as the basis for a story. Writers often use their own experiences to inform the stories they write, but in the end, it's just a matter of crafting the fiction. You may want to use the journal as a reference, perhaps so you can more easily recall specific details that, within the story, will lend an air of authenticity. OTOH, adhering to a journal too tightly can constrict your story by limiting what your imagination might do once you enter the realm of fiction. My advice would be to sketch out a brief outline of what you want the story to be, and then write it.
So, you're trying to take a historical figure and make a fictionalized version of/story based on their life using said journals, yes? First things first: are the journals a source material or will you be working them writing their entries as part of the plot? If they're part of the plot, my first thought would be to imagine them writing a particular entry but then think: did they eat breakfast first? What did those choose to wear that day considering the time of year and the fashion of that time period? After they wrote that entry, what did they do next? My novel is heavily based around my (fictional) main character's journal he keeps in 1660's England and his journal entries are in many of the chapters (It's here if you want to see how I did it: https://www.wattpad.com/myworks/11544455-burnt-bliss-in-progress-&-updated-daily If you're using them as a source material, that's better than any history book because it's life through their own words! Sort of do the same thing. If they wrote about something, they're thinking about it. Take the accounts and turn them into plot points. Let's say a man argued with his wife about a particular matter, so create an original dialogue. What would be say, what is his opinion on this subject, or even look back: which words would he use? Based on what you're read about his wife, how would she reply?
