Basic Information
The narrative Trope known as "Arc Words" refers to an enigmatic word or phrase that appears, unexplained and without context, here and there throughout a series or story arc, and (with luck) is finally explained at or near the climax. A way of building up tension and mystery, as well as an indicator that anyone using the words knows more than they're telling.
Note Arc Words are not the same thing as a Running Gag, a Catch Phrase, or even just a phrase that ends up popping up a lot due to being used a lot in the plot. Alternatively, Arc Words can be a way to hint at one of the themes of a show, often in the form of a question the characters must find an answer to.
Note that in TV and movies the Arc Words often do not have attention drawn explicitly to them; eagle-eyed/sharp eared viewers are left to notice for themselves. On the show Doctor Who, for example, the phrase "Bad Wolf" appeared as, among other things, a helicopter's callsign, a reference in dialogue to "The Big Bad Wolf", a graffito, and even in other languages (the Welsh Blaidd Drwg, the French Mal Loup, and the German Böser Wolf).
See also Arc Number
Sources
Arc Words explored (with lots of examples) at the TV Tropes wiki
http://tvtropes.org/pmwiki/pmwiki.php/Main/ArcWords
Game and Story Use
- Arc Words are mostly a way for the GM to work some artistry into a campaign. Their presence gives the players the impression that some sort of mystery is afoot, or that the game is more "artsy" or meaningful than yet another dungeon romp.
- The GM could start each session by saying Arc Words. In such a case, the arc words probably refer to a theme you want on the characters mind every session. This cues the players that it's time to cut the out-of-character chatter and dive into the game. Small variations in the opening Arc Words could indicate a plot coming to a head, or a diversion from the normal setting or circumstance.
- A Cthulhu campaign might start each session with the GM voicing the lines "That is not dead which can eternal lie…" or some other memorable bit of Lovecraft.
- A particular plot, enemy group, or type of magic could be marked in-character by recurring use of Arc Words.
- Perhaps it's written in on the first page of the spell books used by a cabal of NPC wizards.
- Perhaps a particular decoration or coat of arms marks the safe-houses for an organization.
- Maybe the phrase is code, and the NPCs are fishing for information or know the PCs aren't in on the big secrets until / unless they respond in kind.
- In uses like this, the Arc Words gradually transition into more of a plot device or clue.
- As with the Doctor Who examples, you may be able to insert your Arc Words in under the players' noses. Here's a few ideas:
- The Arc Words are used as just one detail in a prop hand-out, such as scribbled in the margin, or barely visible in a picture.
- You could translate them into other languages, or use anagrams. One thing to consider, though, is if any PCs are playing a genius, or a linguist, or the like, you may need to give them intelligence rolls to notice it. Trying to conceal such rolls can be tricky. Especially in a game set in the modern day, where a quick internet search should be able to translate any odd words that catch their attention.
- Of course, if the arc words involve some sort of idiom or figure of speech, concealing the meaning (or importance) may get easier. Does the strange graffiti say "Out of Sight, Out of Mind" or "Blind Idiot"?