I'm not sure specifically as there could be various novels with this title. It might be a story that involves two different time periods or events that happen twice in some sort of time - related context.
Begin by choosing a character or a group of characters from 'once upon a time' that you want to focus on in your fanfiction. Then, think about how the 'twice upon a time' concept will impact them. Will they be confused? Excited? Scared? Next, create a setting for your 'twice upon a time' story. It could be a different part of the fairy - tale world or a completely new world altogether. Consider the tone of your fanfiction. Do you want it to be dark and mysterious or light and humorous? After that, start writing short descriptions of the events that will happen in your story. This could include things like character interactions, battles, or revelations. As you write, keep in mind the rules of the 'once upon a time' universe while also adding your own unique twists with the 'twice upon a time' idea.
One common theme is the exploration of alternate timelines. Since 'twice upon a time' implies a doubling of the story - perhaps one that already exists in the 'once upon a time' framework - fanfiction often delves into how different choices in these two timelines can lead to vastly different outcomes for the characters. Another theme could be the redemption of characters. In these types of fanfictions, characters who might have been villains in the original 'once upon a time' setup could get a second chance in the 'twice upon a time' scenario to change their ways and become heroes or at least more morally ambiguous figures. Also, the theme of lost love and its rekindling is popular. Maybe a couple was separated in the 'once upon a time' but are reunited or have a chance at a new relationship in the 'twice upon a time'.
Well, in Twice Upon a Time fanfiction, friendship is a big theme. Characters might form new bonds or strengthen existing ones. This could be due to the various adventures they go through in the fan - created stories. Love is also a common theme. It could be a new romantic relationship or the deepening of an existing one. And then there's the theme of adventure itself. Fanfic writers often take the original setting and create exciting new adventures for the characters to embark on.
They could be brave and adventurous as they navigate through the unknowns of 1983. Since they are from a different time (presumably), they might face difficulties in fitting in, but their determination to understand and adapt makes them interesting. They might also be a bit out of place at first, which could lead to some comical situations as they interact with the 1983 locals.
It builds on the events and themes of the TV episode. It might explore character motivations and subplots that weren't fully covered on screen. Also, it could provide a different perspective or additional scenes to enhance the overall story experience.
First, get to know the original work well. Understand the characters, their personalities, and the overall world. Then, come up with an interesting concept. For example, you could start with a 'what if' scenario like 'What if a character had made a different choice in a crucial moment?' Next, create an outline. Decide on the beginning, middle, and end of your story. Don't be afraid to add your own unique twists.
One common theme could be adventure, as the original book might have elements of it. Fans may expand on the adventures of the characters in their fanfiction.