In speaking with a believer (as in, they redefine "universe" to also be a guiding influence like Fate, whose direction they can feel), they often use the phrase "well that's your reality, not mine" or "it's a reality that you haven't realized yet" and I asked them to start using "viewpoint" instead of "reality." To me (and most, I feel), reality is something we call share and is independent of belief (ie humans cannot fly without help, no matter how deeply I believe it to be true). I think I made a misstep, though, by trying to compare it to something like Alzheimer's: what the patients experience is their reality, because it can be tracked to their brain state, even though it's not part of our reality.

While they didn't call me out on it, I'm still debating it in my mind. MW defines it as "something that is neither derivative nor dependent but exists necessarily" which kind of supports my Alzheimer's analogy, because their depreciated brain cells make their state exist necessarily. However, it's not a shared reality with others in their lives--the patient will swear they've never met someone, when that someone has known them all their life. That example could easily support the mentioned believer's (let's call them Terry) definition of reality, because it necessarily exists for them, and Terry's so convinced that we probably could track this impression of Fate to a brain state.

Thoughts? Maybe you have a different way of looking at it that'll help differentiate the two situations?