What's a good way to get to know your character?

Basically: iteration. Whatever detail I come up with about my character, I always look for ways that this detail manifests differently for my character than the same detail would manifest in another character.

Spoiler

I use D&D alignment and MyersBriggs personalities to map out my characters, and with "only" 144 combinations of the two, any type I come up with is going to be shared by a bunch of other characters.

My first-person peripheral narrator, Alec Shorman, is a Lawful Evil ESFP, but so are Darth Vader (Star Wars) and Don Maroni (Gotham). Darth Vader is a "Law and Order" Lawful Evil, an ESFP who looks ESTJ at first glance, and is willing to play second fiddle to the Emperor, whereas Maroni is an "Honor Among Thieves" Lawful Evil, is obviously ESFP, and is pathologically compelled to make it to the top or die trying.

Alec is more like Maroni is that he's a criminal, not a tyrant, and in that it's obvious that he's ESFP, but he's also more like Darth Vader in that his life's goal is to help his friend Charlie (my MC) become Queen of the Hill by being available for whatever she needs him to do.

Charlie herself is a Neutral Evil ISTJ like Dexter Morgan, but where Dexter is a vigilante, Charlie would go on a mass shooting for the right price.

 

Lots of great ideas here. It seems almost all these could work, because it's about more time needed with this character with any type of interaction you choose. Like when a real live person you've barely met suddenly becomes your roommate. It's awkward guesswork at first -- you don't even know this person -- until various random interactions over time start helping you know that new roommate in far more depth. Will just add these two: 1. Marry him for a few days. Meaning as you go about your day, ask him if it's his turn to make dinner, apologize for being a little late coming home, or ask which movie he'd like to watch together that evening, or whatever you do in your life where you'd engage with a spouse's response or reaction. How would this character respond? That hopefully won't lead to a divorce. 2. Keep his diary for him for a bit. Be him, and write in a daily journal about his deep thoughts and viewpoints on world events or daily irritations. Nothing like taking a peak at someone's diary to know more about them.