The existence of the character described in the books is a tricky question that cannot be directly answered. Depending on your definition of existance, it either exists, or it doesn't. However, this does not necessarilt disprove Descartes' statement.
Let's say the character does not exist, this means there is no character going through the Cogito. Descartes' statement holds no meaning in this situation.
let's say the character does exist, it is going through the Cogito, which according to Descartes means there is some object that has to exist for these thoughts to arise. And there is! The books that you have painstakingly written exist somewhere to describe the thoughts of the character exist somewhere in the physical world (or whatever hypothetical world or universe you have theorised).
Is this not exactly Descartes' point? If we interpet it broadly: Whenever thought arises, this thought must materialise from some existing state or presence, thus proving the existance of 'something'. To give this object the identity of oneself is perhaps a bit of a stretch, but one could argue that if this state or presence creates these thoughts it can usually be associated with 'self' in whatever way you want to define it.
Let's say the character does not exist, this means there is no character going through the Cogito. Descartes' statement holds no meaning in this situation.
let's say the character does exist, it is going through the Cogito, which according to Descartes means there is some object that has to exist for these thoughts to arise. And there is! The books that you have painstakingly written exist somewhere to describe the thoughts of the character exist somewhere in the physical world (or whatever hypothetical world or universe you have theorised).
Is this not exactly Descartes' point? If we interpet it broadly: Whenever thought arises, this thought must materialise from some existing state or presence, thus proving the existance of 'something'. To give this object the identity of oneself is perhaps a bit of a stretch, but one could argue that if this state or presence creates these thoughts it can usually be associated with 'self' in whatever way you want to define it.