Only One Can See

Don't worry, you're only ｓｅｅｉｎｇ ｔｈｉｎｇｓ.

When only one person can see certain things like ghosts, fantastical creatures, or other things that are hidden from everybody else. If they're seeing these things and they aren't real, then the things are hallucinations and they're a Lunatic. This can be because this person is the Chosen One and it's part of their destiny to be the only one who can see or they have a Unique Ability that allows them to see. It's also possible that both are true. Sometimes, when this person is interacting with things only they can see, others around them may think they're a Lunatic if they don't understand what's going on.