I hope this is the right place to ask this
I've been researching a lot about the "show, don't tell" phrase. For the most part, I understand how it works: saying "Alice was angry" simply tells the reader what the character is feeling, but saying "Alice's face grew hotter as she grit her teeth and punched the pillow in successive and strong jabs" shows the character's emotion without stating it outright. But I'm having some trouble conveying a specific information through actions instead of words.
For context, in my story there's this character who gives nicknames to everyone he meets, and never calls them by their real names. He does this because he firmly believes names have meaningful power, that they're the essence of a person's true self – and since an event in his past caused him to become disillusioned with other people, this character nicknames everyone as a way to distance himself from others, to avoid forming deeper connections with them. 'If you don't call people by their real name, you won't get attached to them' is his line of thinking, which is flawed, but works for him.
My problem is, how do I show this very particular trait of his in the story without making him explain it or telling it in the narrative?
Source: reddit post