I use psychology to help my characters to sneak into the reader's mind at a subliminal level. Here's a partial list:
1) The character who dislikes the protagonist the most has the same character flaw as the protagonist. This is often referred to as "mirroring".
2) People have "tells" when they're lying and withholding information. Pursing their lips, closing their eyes for longer than necessary, blinking rapidly, sweating, and looking away (purportedly to the right if they're right-handed) are all different "tells". Sprinkling this into descriptions of people lying gives a heads-up to the reader that something's up.
3). Archetypes -- or more correctly -- archetypes in the Jungian sense. Joseph Campbell believed in a universal story, and in his story, roles that correspond to Jungian archetypes such as the hero/heroine, the mentor, the trickster, the innocent, and the magician. To some extent writing archetypes comes subconsciously, but it helps to be conscious about it.
4) Dreams and visions. I'm a Jungian at heart, I'm afraid, and that means that I impart important information about the psyche of my protagonists through their dreams. As is true to dreams, the sequences are symbolic, fragmented, and often mystical.
I have fun with psychology; my characters have no idea how much psychology goes into them.
Originally written January 28, 2018