Non-Linear Immortal
Imagine you are an immortal person, who has been alive ALWAYS. Immortal from the beginning of everything, to the end of everything. The problem? You don't experience time in a Linear way, unlike humankind, who experience all of time in a linear, sequential way. For you, everything is present to your mind at all times and all places that you ever have been and ever will be.... EXCEPT... you have now been forced into an ordinary human form (though an immortal one) and are now capable of seeing time in a linear way; but you also still see it non-linearly, and having all of it both happening and also NOT happening all at the same time is literally maddening.
One day you wake up in the psych ward of a hospital and decide that none of it is real except NOW. You may know everything that will ever happen to you, both past and future through eternity, but you now conclude that both past and future are nonexistent illusions. How do you convince the doctors that you are 'cured' without referring in any way to what made you 'crazy' before now (because you won't admit that there exists a 'past' in which you were crazy), and without talking about what you are going to do if they let you out (because the future is an illusion, so why plan for it)?
Or maybe you decide instead to either stay or break out? Either way, you can't really plan it any more than you can think ahead about what to say to the doctors.
[I may actually have characters in some stories who would be capable of viewing time non-linearly, but... this particular scenario (and similar situations) is one I am not using, and I would be interested to find out how other people would write a character like this.]