Unless you’re Karl Ove Knausgard, writing entails getting in touch with life outside of yourself. That can present problems in fiction. Why? Most writers’ lives just are not that exciting.
Lynda La Plante, the crime novelist responsible for the series Widows and Prime Suspect, has a simple solution for finding out what you need to know:
If you want to find out something you go to source. If you want to know what a man serving life for murder is like, call your nearest prison and register as a visitor … That’s what’s so exciting as a writer, if you put yourself out there, you come home with the goodies
So if you want to truly engage with your invented characters, go find their closest real-life corollaries and talk to them. That’s how you get the goodies.