A lot of people use semi-colons wrong because they know there’s supposed to be a pause in their sentence that they know isn’t quite a comma, so they think it must be that mysterious semi-colon. Usually, it’s actually supposed to be an em dash (—), which in some ways is more mysterious!
The em dash is the longest of the three dashes and most often used for interruptions. Interruptions in speech, in action, in thought. It’s also a great syntax addition for fight scenes, since it makes the narrative seem quick and unexpected and jolting from side to side like a fight scene should be. Read your em dash sentences out loud until you get a feel for how its pause compares to the pause of a comma. It’s a heartbeat longer. If a comma is one beat of pause, then I see an em dash as two beats of pause.
In this first example, the em dash is used to give an aside to the reader. It’s like a btw sort of moment, which can sometimes be replaced with commas or parenthesis. I think the em dashes are most suitable when your aside is decently long.
Her neighbor, Frank, is always blasting music.
Her neighbor—the one who always blasts the music—is named Frank.
My mischievous neighbor, Vince, seemed to have a knack for graveyard cavorting.
Vince—more often called (in a raised and angry voice) Vincent Price Ramsey—seemed to have a knack for graveyard cavorting.
Next up, here’s the em dash as a replacement for the semi-colon. Kinda like a slang or shortened sentence. Semi-colons have to connect two independent clauses—meaning each side of the semi-colon could stand alone as its own complete sentence. If you don’t want to do that, try an em dash:
I thought hanging out would be great—a chance to finally see the city, just like Aunt Lillian wanted.
I thought hanging out would be great; it would be a chance to finally see the city, just like Aunt Lillian wanted.
There was a headstone hardly a foot from where I’d emerged—dark grey stone a few inches thick and maybe as high as my knee.
There was a headstone hardly a foot from where I’d emerged; it was made of dark grey stone a few inches thick and maybe as high as my knee.
Sometimes, you can use an em dash to have a speaker correct themselves, or interrupt themselves to amend their sentence.
I could see the blur of the graveyard behind him—through him—
Similar to the last example, it can be used to interrupt a sentence in order to add additional information about the sentence. Often you can use a comma in this situation, too, so try to think of syntax and how that additional beat of pause changes things. In this case, Alice has just seen a ghost for the first time, so her mind is a bit too shocked for the normal pause of a comma. Read both. Doesn’t the one with the em dash sound more shocked or surprised, while the comma makes it sound like a simple observation?
He was glowing pale—almost tinged in cold blue.
He was glowing pale, almost tinged in cold blue.
Of course, it could be an interruption. It could be someone interrupting another in speech, one action interrupting another, or a character’s thoughts interrupting themselves. Here I’ll include the sentence with the em dash and the sentence following, so you can see the thing interrupted and the interruption.
You can have an action interrupt a character’s thoughts. For the first one, Alice is in a creepy situation and completely focused on something else, so when something touches her elbow, she’s shocked out of her thoughts. For the second one, Tristan is listening for an enemy when the enemy makes a move and startles him into action.
As far as I could tell it was some kind of berry—
An icy contact on my elbow broke my resolve, and I screamed until an equally cold hand clamped over my mouth.
The night was still, and yet—
Something whistled through the air. Tristan jerked backwards, narrowly avoiding an incoming dagger.
Here we have one character interrupting another in dialogue. Pretty self-explanatory.
“I’m not going to—”
Mom’s voice in the receiver cut me off. “At least consider it.”
“After all, you’re only a—”
“If you even say girl,” I interrupted, “I’ll stab you, I swear.”
The next one is part of a fight scene, so Alice’s thoughts are interrupting themselves as soon as she thinks them. She throws up an idea, “iron,” but interrupts herself from further exploring that idea, and instead casts it out. In a fight, you don’t have time to think out long, eloquent ideas. Your thoughts should come in fragments. Stab. Punch. Dodge. Swing. Would this work? No. How about this? Maybe. The em dash can help get across this uneven jolting of thoughts.
Iron—no use. I’d dropped the knife when her damn vines ensnared me, and the nails were in my pockets and out of reach. Blood—there were possibilities there.
Continuing in fight scenes, em dashes can have action interrupt action. Don’t just throw them in willy nilly, but if you have a chance for an em dash, jump on it. Instead of a word like “suddenly,” it makes it feel suddenly. Ups the tension. Em dashes are about interruption, and what is a fight scene but two people interrupting each other’s attempts to kill the other? This is especially useful for the last line in a paragraph during a fighting scene, because it’s a nice place to have one action interrupt another.
I snatched it—slit across my hand—
And stabbed her through the heart.
His swords whistled through the air—
A clean “X” appeared on the imp’s back, severing its body into four neat chunks.
So yeah, I’m basically obsessed with em dashes and I use more of them than the majority of writers. (At 72k words, my current project has 22 semi-colons and 344 em dashes. So. Yeah. Not to mention the length of this post…) Em dashes are way cool and can add a lot to your writing even though they’re just another form of punctuation. Syntax helps your reader into the mindset you’re going for, and em dashes can be a great, powerful part of that syntax!