Yes, essentially. Authors wanting to play within the Sherlock Holmes space are competing with so many adaptations that already exist, they must be asking themselves how can they still surprise the audience, how can they bring a novel interpretation, how can they push and play with the characters when the audience is so familiar with the canon world as well as dozens of adaptations and retellings. Their story must still be familiar, hecause the audience is specifically coming to the work expecting a shelock holmes story but also be new in some way, (this is of course to a lesser or greater degree as well, and authors may ir may not be trying to attract the entire holmesian fanbase, but sections of it)
Then of course from the premise of Wouldn’t It Be Interesting If Sherlock had a younger sister, is a disruptive change to the canon world but can fit in considering how secretive Sherlock is about Mycroft. Bringing in a sister then obviously leads to choices about who she is, if he knows about her, what happened to her, why they are or aren’t working together/ in contact. And those choices can go backward and forward in the story construction:
Backward direction construction might look like:
The author wants Sherlock or other characters to have certain traumas, emotional responses, An explanation to his motivations, a driving force in the story. his sister, disappeared, died, ran away, was hidden amd then returns can be the causation of that characterization of Sherlock and others in the narrative, or the sister can be the secret cause of events going on around Sherlock tha he must discover.
In other words: here’s the conclusion of the narrative/character development how do we get here and then invent the pieces to get there.
Forward direction construction:
Or here’s Sherlocks younger sister as The author imagines her, what impact does she have on the world and characters we are familiar with.
this is the opposite, heres the set up, the pieces are on the board, how do they act and influence each other?
Both are probably happening when authors write though story ideas may come about primarily from one of those methods and then are further crafted using the other.
This is certainly how I think about writing within others IP as a fanfic author
