In a story I'm working on, I'm adding a side character to travel with the two main characters because I realized I didn't have very much planned for actually showing who the main characters are and how they react to difficult people. So the character herself actually serves a purpose so that's not what I'm worried about, just thought I'd include that.
I'm worried about a major detail regarding the character. She believes she has an "evil spirit" attached to her, but he's really just a figment of her imagination. She sees him most nights in her dreams, and actually talks to him, grows with him, you know, like it's a real person inside her head. I was thinking she'd even occasionally see him in real life too.
This is where the issue comes up. In stories set in kingdom fantasy, readers tend to see certain things like imaginary friends and gods, as magic and assume they're actually real. So how could I make sure readers know that this "person" isn't really real? I'm worried that if I include this character with that detail then I might end up spending too much time or too little time trying to show that the spirit isn't real.
So should I spend time making sure readers know that the spirit isn't real, or should I just hope they can infer that the lack of other magic means this isn't magic either?