World Building: Weaving Plot Threads

A good story never has just one thing going on. To make the world feel alive and add depth to the characters you'll often find that two or more things are going on in parallel as a story progresses. You see this a lot in books, TV, and film where the action jumps between separate but related groups of characters and follows them for a short time while they do something important before the story's focus moves on to a different group. At certain points these threads intersect but it can be a long time in between and when they do it's usually because something important is happening.

In interactive storytelling this kind of narrative structure can be difficult to pull off. Your audience are active participants instead of spectators, so you can't have the action move away from them to go focus on another group unless you split the party. As any good GM knows you don't ever split the party lest a truly horrible fate befall your campaign. Instead of pulling the focus away to follow other characters, telling these secondary stories must be done more subtly. Players will likely never get the full story of what's going on outside of their view, but they can get windows into it through interactions with NPCs, active information gathering, and times when the action of another story thread intersects their own.

There's a great example of this in the movie Shaun of the Dead: The protagonist Shaun and his three friends are fleeing a zombie apocalypse on foot when they round the corner of a building and run into another survivor who is an acquaintance of Shaun's and three of her friends traveling in a different direction. They briefly tell eachother of their survival plans and then the other party go on their way. The story is told entirely from the point of view of Shaun and his party so we never see what happens to this other party before or after their brief encounter. You can't help but feel though that they're the heroes of another story running parallel to Shaun's and wonder what will happen to them. Events like this are spread liberally throughout the movie, often happening in the background as the action moves past them. They're never directly focused on but they give the viewer an impression that there are other forces at work, other events going on, and that the world does not revolve around the central characters.

A typical way to construct a story like this is to have two main plot threads, the "alpha plot" and the "beta plot" and a plethora of mostly-inconsequential background events that are loosely related to the two plots but serve primarily to add flavour and make the world seem larger. Additionally, these plot lines may tie into an larger storyline, often called an "arc". A very well layered story may have several arcs weaving their way through several episodic plots.

Alpha Plot - The Heroes' POV

This is the story your characters are in direct control of. The alpha plot is their story and most of the events that they participate in should contribute to advancing and steering this plotline. When planning a campaign this plot will have the greatest level of detail and have the most possible directions for the players to choose. If you're playing episodically, this plot starts at the beginning of an episode and the episode ends when this plot is concluded.

Beta Plot - The Under-current

This is the story happening just outside of the party's field of view. It's driven mostly by NPCs and the side-effects of events in the Alpha Plot. The party get glimpses of this plot from time to time at points where it intersects the Alpha Plot. Often NPCs that are important to the Alpha Plot will be important to the Beta Plot as well, and probably know more about it than the players. If your story has villains of the scheming type it's likely the beta plot will feature a gambit of some kind that only comes to the forefront late in the Alpha Plot.

Arcs

Most long-running episodic adventures will have story arcs. These are much longer running pieces of narrative that individual episodes' Alpha or Beta plot will relate to in some way. A highly episodic adventure may have one or more story arcs as the only thing linking individual episodes together. An adventure with longer episodes (or chapters) may have several arcs interacting within a single plot. For examples of different kinds of arcs, I'm going to use the movie Snatch (apparently I have a thing for British comedy).

Arcs: Character Arc

A character arc is simply how one individual grows and changes over time. A well-constructed character arc will spans several episodes and shows the audience how the events of those episodes have changed the character within the parameters of their persona. A character arc might follow a young, reckless warrior through a string of battles (episodes) where he learns restraint, honour, and strategy and grows into an accomplished tactician. A different kind of arc might follow a cunning and manipulative leader as she gains rapidly power, only to fall from greatness into madness as her scheming pushes away allies until she is left with nothing.

In Snatch virtually every character undergoes some sort of arc, but the best examples are Mickey (the Traveller boxer) and Avi (the American jeweler). Both of them start off just living their lives, get wrapped up in either the Boxing Match Alpha Plot or the Diamond Heist Beta Plot, and end up significantly burned out and arguably worse off than when they started.

Arcs: Item Arc

An item arc happens when an inanimate object of some importance passes through several people's posession and impacts the story of those around it in some way. The One Ring from The Lord of the Rings is probably the best-known example. Its arc passes through the story of the War of the Ring, the history of Gondor, and The Hobbit, before finally becoming central to the Alpha Plot of The Lord of the Rings.

In Snatch the stolen diamond's story arc starts off in central focus but quickly becomes buried in the movie's tangled plotlines, driving the action only occasionally but always in a significant way, before ending up once again the center of attention at the very end of the film.

Arcs: Prophecy Arc

This kind of arc happens when something is foretold in an early episode and hangs like a shadow over the plot for many episodes to come. Often these arcs are the longest and can have profound influence on the plot as parties try to either cause or prevent the foretold event. When effectively used,  prophecy arc can fade entirely into the background but never leaves people's minds. Prophecy arcs are also the most likely type of arc to cause unexpected twists to happen.