Dialogue is where historical and mythic fiction either soars or sinks. Get it right and the reader hears voices across centuries; get it wrong and your medieval blacksmith sounds like a pantomime extra. The good news is that authenticity on the page is rarely about literal accuracy. It is about creating a convincing illusion — one that respects the past without asking modern readers to learn a second language.

Why "Thee" and "Thou" Usually Backfire

The most common mistake is reaching for the nearest archaic pronoun and scattering it like seasoning. "Thou" and "thee" were not simply "you, but old". In early modern English they marked intimacy, social superiority, or deliberate insult. A servant might say "you" to a master and receive "thou" in return — the pronoun was a small act of power.

Use those words arbitrarily and you create two problems. First, you are probably wrong. Second, every time a reader meets "thou dost", they are nudged out of the story and reminded they are reading a costume drama. The same applies to "methinks", "verily" and "forsooth" — words whose main modern function is to signal pastiche.

A better approach is to write in clear modern English and let the texture of speech do the work. If your characters address one another with careful formality, avoid contractions, and choose their words with weight, the reader will feel the distance of time without tripping over it.

Rhythm Does More Work Than Vocabulary

Read a passage of dialogue aloud. Does it sound like a person speaking, or like a museum plaque? Historical speech differed not only in vocabulary but in pacing, indirection, and the amount left unsaid.

Try these adjustments:

• Vary sentence length deliberately. Long, balanced clauses suggest a considered or aristocratic speaker; clipped fragments suggest someone practical or wary.
• Use fewer contractions for formality, more for intimacy. "I will not" lands differently from "I won't", and that difference can signal class, mood, or the state of a relationship.
• Let characters talk around a subject. In many historical societies, directness was rude. A marriage negotiation or a betrayal might be conducted in hints, proverbs and polite deflections.

Keep the feel of that indirection without making the reader decode it. One or two unfamiliar words per page is a spice; a paragraph of them is a wall.

Swearing, Slang and the Authenticity Trap

Sooner or later every writer looks up what people actually said when they stubbed a toe. The answer is often disappointing: either the words are now meaningless, or they are so shocking they would change the tone of your book entirely. Medieval oaths were frequently religious — "by God's bones", "God's teeth" — and their power came from blasphemy, not obscenity.

You have three practical options. Use mild, period-flavoured oaths that modern readers grasp instantly. Invent a small vocabulary of your own and use it consistently. Or allude to the swearing without spelling it out: "he said something foul enough to make the priest cross himself." That third option is often the strongest, because it lets the reader imagine something worse than you could print.

Titles, Address and the Grammar of Power

How characters address each other is a characterisation tool. A single "my lord" or a deliberately dropped title can reveal resentment, affection, fear, or a shift in fortune. Build yourself a small reference for your setting: how does a child address a parent, a soldier an officer, a stranger a priest? Then decide where your characters break the rules. The moment a servant calls her mistress by her first name is a moment the reader will remember.

Mythic Voices: Gods, Heroes and Oracles

Mythic dialogue has more licence than historical dialogue, but it follows the same principles. Gods should not sound like fortune cookies, and prophecy works best when it is specific enough to unsettle and ambiguous enough to come true in retrospect.

Draw on the techniques of oral tradition:

• Repetition and epithets. "Grey-eyed Athena", "the wine-dark sea" — these are not decoration but the rhythm of spoken verse.
• Formal boasts and laments. Heroes and mourners speak in set pieces. Let them.
• Riddles, oaths and curses. These carry weight because they are bounded, not because they are long.

Even a god needs a personality, though. A deity who speaks only in pronouncements becomes tiresome. Give your immortals opinions, grudges and a sense of humour; it will make their power feel more real, not less.

A Practical Checklist for Drafting

• Read every line aloud. If you stumble, your reader will too.
• Cut archaisms that exist only to signal "olden times".
• Keep unfamiliar words to a minimum and make their meaning clear from context.
• Use address and titles to show relationships and shifts in power.
• Decide what your characters would never say, and let that shape the scene.
• Give mythic speech rhythm, repetition and personality — then break the pattern when it matters.

Finally, trust your reader. They do not need a glossary. They need voices that feel human, constraints that feel real, and a story that carries them past the unfamiliar and into the lives on the page. Get that right, and the centuries between you and your characters will shrink to almost nothing.