The contents of fiction may not exist, but fiction itself does, and it exists as the concept of what it contains.
Therefore, the fictional is conceptually real.
Fiction is conceptual existence.
Falsehood is strictly conceptual existence presented as explicit existence.
An illusion is only an illusion if presented as real.
A statue is only an idol if presented as a god.
A fiction acknowledged as fiction will be a real fiction.
A fiction presented as a reality will be a false reality.
Willing suspension of disbelief is not the same thing as belief. It is the entrance of the mind into the real concept of something unreal.