Best friend character dynamic!!!
She's the tyrannical queen of a large kingdom, and she has had people executed for talking $h!t about her. He's the general of the kingdom's military, and he's allowed to say anything he wants to say about her. No romance. No "friends with benefits". Just two chaotic besties who spill tea and kill people.
Bonus points if she has anger issues and he thinks her bull$h!t is hilarious, but he can't show it without ruining his reputation as emotionless.
Extra bonus points if she has some really angsty backstory, and he has one too.
Extra extra bonus points if he originally took the job because of the money, and he didn't care about her, but he learned that she was super cool and he became her bestie.
Extra extra extra bonus points if she finds out about that and thinks that he doesn't care about her.
EXTRA EXTRA EXTRA EXTRA bonus points if she's lesbian and he's gay
EVEN MORE EXTRA bonus points if the queen has dating issues but has a good relationship with her family, and the knight has a good lover but a $h!tty family.
EVEN MOREEEE EXTRA bonus points if they are brutally honest with each other. Like, the queen will send a picture of a girl she finds attractive, and he'll say that the girl is the most hideous person he has ever laid his eyes upon.