While trademarks and copyrights both offer intellectual property protection they project different types of assets.
For your universe filled with stories (and assuming characters), you would likely file a copyright since that falls under an “original creative work”. Other examples includes a play, novel, song, comic, choreography etc…).
This protection would last the lifetime of the author (you) plus 70 years.
Additionally, with a registered copyright, you can enforce federal copyright protection in court.
A Trademark on the hand is what you would use to protect the name or logo of your artwork. Trademarks require a maintenance fee and is renewable every 10 years.
Hope that helps! If you’re looking to buy a trademark and/or copyright feel free to check out. Our on-demand service offers free initial consults and fixed-fee legal services.
Best of luck. Sounds like a super interesting project 🙂