I can already hear at least once pantser preparing to explain why they don’t do this. If it helps, person with fingers at the ready, you’re right. Character biographies don’t work for everyone. They aren’t even universal because everyone has their own way of doing them because every author has different needs. Some even change from story to story or as our own skills grow. I know that I’ve been all over the map as you’re about to see.
Character bios are where I started since tabletop games were my first inspiration alongside fantasy books. This resulted in my originals being more about numbers stats and basics instead of depth. I had hair, eyes, height, weight, skin, and physical attributes with very little variety. I couldn’t tell you what the real difference between a 4 and 5 in strength really was. A 1-5 ranking was probably a dumb choice. I added gear, personality, and skills to the bottom then left it alone. I used this for Legends of Windemere too, but I had notes on other papers for evolution. This system didn’t change for about 20 years because I spent most of my time doing quick outlines of other stories without doing any meaty bios. By the time I came back to that tactic, I no longer cared about the physical stats. I changed it to be a paragraph explaining history, role in story, goals, key events, general appearance, personality, and unique pieces of gear. This gave me more wiggle room and it created the possibility of subplots as I wrote along. It also reduced it from one character per page to 2-3 depending on importance.
The benefit of character bios is the same as any planning activity. It gives you a direction to go with the character. You get a sense of how they fit into your story and world. The writing stage doesn’t begin with you shadowing an unknown figure, but walking alongside an acquaintance or friend. Things may very well change as you go along because you don’t factor all story events into the bio. It’s only a guide for that character. One could even call it a starting point because things can be altered. Everything from hair color to personality is fluid until you hit publish, so never think that your bio is the end of creation. It’s only something you can go back to if you need to revisit a character’s origins. If you have to stop writing that project for a long time then these can be very useful in jogging your memory. This means you can add notes to it as well. Whatever it takes to help you stay consistent.
Another use for character bios is with promotions. You can easily turn one into a behind-the-scenes blog post or video. People like these peeks into the process. You can show how things changed from the origins, which tends to happen. Turn in into a discussion or a lesson about the character instead of an info dump. We avoid those in books, so it’s best to do the same when promoting too. Of course, you can do this without a bio, but it doesn’t hurt to keep track of the evolution. For your own amusement, you can go back and see how you and the character grew.
So, does anybody else create character bios? What’s your style?