Weston, Mississippi is not a real town. People ask, and I understand why, because it feels like one. It has a bookshop and a diner and a bar out past the county line. It has a swamp the sensible people stay out of after dark, a fortune teller who cannot tell fortunes, and a warehouse where a body turned up in the fog. I could draw you a map.
What Weston actually is, is four or five towns I have known, with the names filed off and the streets rearranged so that nobody can prove anything.
That is the trick, and it works for people as well as places. You use what is real. You use it hard. Then you move it just far enough that it becomes yours and stops being theirs.
Keep the senses, change the map
A real place gives you what you cannot make up. The way the heat sits on the highway in August so the far end of it looks wet. The sound gravel makes under a truck when somebody pulls in late. Which pew the same family has sat in for sixty years, and what happens when a visitor sits there by mistake. Take all of it. Take the smell of the gas station and the fact that the courthouse clock runs four minutes fast.
Then change the map. Move the river to the other side of town. Put the church where the school was. Give the main street a different name and take a building out. You will be surprised how little this costs you and how much it buys. The reader gets a place that feels lived in, because the details came from life. You get a place you can do anything to. You cannot burn down the real hardware store. The man who owns it goes to your church. You can burn down the one in Weston any afternoon you like.
People are made of three people
The characters who walk off the page are almost never one person you know. They are built. The walk of your uncle. The thing your third grade teacher did with her hands when she was disappointed in you. The thing a stranger said at a gas station thirty years ago that you have never been able to forget. Stitch three of those together and you will have somebody real enough to argue with, and nobody at church will recognize themselves, because nobody is in there whole.
There is a kindness in this, and a freedom. The kindness is that the people who trusted you with their lives do not wake up as villains in your novel. The freedom is that a character built from parts can do whatever the story needs. Your uncle would never have robbed the bank. The man with your uncle's walk might.
Give them the want the real person hid
Here is the part that turns a portrait into a character. Real people keep their wants hidden, mostly, even from themselves. A character has to let the want show, at least to the reader, or nothing happens. So when you build someone from three people, ask what the person underneath is after. What would they do to get it. What have they already done that they would not admit to. The waitress who calls everybody baby is a detail. The waitress who calls everybody baby because she is watching the door for a man who said he would be back in 1988 is a character. The detail came from life. The want came from you.
The one you are not allowed to change
Every writer has a person they are afraid to write. A parent, usually. A first love. The friend who did not make it. You are allowed to leave them out. You are also allowed to file the name off, give them a different town and a different trade and a different thing to lose, and write the truth about them with every fact changed. Most of the writers I have worked with are surprised to find that the second way is the more honest one. The facts were never the point. What you knew about that person was the point, and that survives the move. It might be the only thing that does.
Go stand in the middle of the town you know best, or the one you left. Write down five things about it you could not have made up. Then draw the map wrong on purpose, and put somebody in it who wants something they should not have. That is a first chapter. It might be a book.