Grammar question: Genitive case noun followed by parentheses

How do you correctly write sentences that put phrases in parentheses between a noun in the Genitive or “possessive” case and its object?

For example:

“Superman’s (a heroic cartoon figure) only weakness was Kryptonite.”

The statement can be rearranged to say “Superman was a heroic figure whose only weakness was Kryptonite,” but there might be some statements that cannot be thus rearranged without seeming awkward.

Well,could you give some more additional statements that attach to this setence?

We need some examples of the type of sentence you’re talking about.

It’s also possible to say, “The heroic comic book character Superman’s only weakness was Kryptonite.”