I highly agree with Jenkins's opinion on the definition of transmedia storytelling: "Transmedia storytelling represents a process where integral elements of a fiction get dispersed systematically across multiple delivery channels for the purpose of creating a unified and coordinated entertainment experience. Ideally, each medium makes its own unique contribution to the unfolding of the story." Jenkins mentioned that we, as grassroots, factor the expansion and the spreading of the transmedia storytelling. In my opinion, the promotion and the circulation of the storytelling of one media is closely dependent on the grassroots.
As Jenkins said, the possibility of initiation to transmedia storytelling needs the original story's group of fans. Only if people like the story, the creator of the story will continue the development of the story world. This can be explained by so many cases. Take the movie Saw as an example, if the first Saw movie was not successful, the producer would not spend the rest of 6 Saw movies trying to explain all the unresolved clues and characters in the franchise.Also, fans contribute to those storytelling. When the second Saw movie came out, some avid Saw fans already guess the identity of the operator who implant the key into the first victim's eye socket in Saw2, some even predicted what happened to the doctor in the first movie who was never mentioned in the franchise until Saw 7. Words have been spread on Internet, and that fan based comics as well. Eventually, Saw video games were made too. And all of this contribute to keep the series moving.
In general, the formation of transmedia storytelling depends tightly on the dispersion of the story itself, and it needs the effort of both the grassroots and the story creator to survive. The interconnection of fans incites the brainstorm of the story, and the creators have an easy access to more inspiration to keep the storytelling going based on the favor of its fans.