Writing fan fiction has become a popular pastime for many fans. But when does doing so cross any legal lines? Taking an existing copyrighted piece of work and adding to it or changing it in any way could create an environment ripe for possible commercial litigation. There are laws in Canada governing such practices -- laws that protect those who create bodies of work from others either plagiarizing or stealing them.
Fan fiction is the creation of a story using characters or a storyline that has already been created by someone else. That could mean from a novel, a TV show, movie or play. Most originators of work don't take kindly to fan fiction that has been posted on social media sites. Even though some fan fiction is well written, it still doesn't mean original bodies of work can be used without the permission of the copyright owner; however, some authors have actually welcomed the posting of fan fiction – J.K. Rowling, for one.
The problem lies not with the writing of fan fiction, but in the dissemination of it. Most often, permission from the copyright owner is never obtained which can cause all kinds of legal ramifications. Obtaining permission before posting on social media would go far to eliminating any possible legal problems.
Some posters actually charge money for their fan fiction which fuels the potential for commercial litigation even further. Residents in Canada who are unsure of the rules that govern copyright law might find it helpful to talk to a lawyer who has experience in such cases. It is better to be safe than sorry when thinking of posting fan fiction online.
Source: findlaw.ca, "Can you write fan fiction without violating copyright law?", Accessed on Nov. 3, 2017