I have an idea for a children's book which follows the plot line of using a character who is a lot like the (presumed) audience to introduce a character/culture that is not very much like the presumed audience. Is this form of writing copyrighted or even something that can be copyrighted? Thanks!
The form cannot be copyrighted. A specific work following that form can be copyrighted, and in fact is copyrighted as soon as you have a durable draft (durable meaning it will persist in some tangible form and can therefore be presented before a court, if necessary - A picture composed of trails of smoke would not be a durable medium).
learn what can and cannot be copyrighted here: www.copyright.gov and about trademark protection here: www.uspto.gov