What do trademarks have to do with authorship? Trademarks signify sources of production. The question come up with authors producing serial works who are interested in creating brands. Trademarks for authors can be perfectly reasonable. While single works are not eligible for trademark registration serial works are. Personal names are not registrable as trademarks but titles may be if they identify a series or the names of characters who appear in series. In this way copyright and trademark can work in tandom.
As a practical matter, they co-exist as valuable assets. Traditional publishers demand rights that may include dramatic, audio, motion picture, television, and merchandising. If rights are retained by the author the pool of potential licensees is likely to be greater and the literary property more valuable if the author has also secured a trademark. Caution: be sure the corresponding domain name for the contemplated trademark is available BEFORE applying to the trademark.
Note: We are deleting the balance of this essay with the view of rewriting it.