Dressing up together for Halloween.

Dressing up together for Halloween means granting yourselves a rare permission: playing someone else for one night, without having to explain yourselves. On 31 October everyone wears a mask, and nobody will ask why you've got fangs or a cape. It's the best excuse on the calendar to try role play as a couple.

The festival goes back a long way. On this date the Celts marked the start of the dark season, a night when, so they said, spirits returned among the living, and legend has it that people dressed up to go unnoticed. In costume, you're no longer quite yourself, and that's precisely what makes certain things possible.

No need to stage a production, though: two costumes that play off each other, a conversation beforehand, three lines of scenario and a few fits of giggles.

Because it's no longer you asking, it's your character. The vampire is allowed to be imperious, the witch insolent, the masked stranger blunt, when you'd never have dared half their lines. The costume shoulders a good part of the awkwardness.

Psychologists have often observed it: behind a mask, the fear of being judged drops a notch. You stop wondering "what do I look like?", because you already know the answer: someone else. That little distance is enough to let out a desire you usually keep to yourself.

Then there's the way you see each other. Finding your partner as a hunter in a long coat or a creature with smoky, kohl-dark eyes is like meeting a stranger you nonetheless know by heart (and the socks at the foot of the bed vanish in an instant).

The mask doesn't hide who you are, it gives you permission to show it.

The right Halloween couples costume is one that already tells a story for two. Two matching skeletons raise a smile, whereas two characters who play off each other create tension straight away: one lures, the other resists, one seeks, the other hides.

• The vampire and their prey: the great classic. One seduces, the other lets themselves be approached... or not, and it all comes down to the neck.
• The witch and the inquisitor: one comes to extract a confession, the other casts a spell, and soon nobody knows who holds the power.
• The hunter and the creature: werewolf, demon or forest spirit, facing the one who tracks it down. The pair for hide-and-seek in the half-dark and a capture both of you want.
• The Venetian masks: two strangers at a masked ball. In Venice, a mask once let you mingle with the crowd incognito, whatever your rank: that's the whole spirit of the game.

The roles aren't handed out in advance: a woman makes a magnificent vampire, a man makes very convincing prey, and these pairs work just as well for two women or two men. The only criterion: that each of you actually wants to play your own character.

A little test before you buy anything: describe your character in one sentence ("a countess who hasn't dined in a century"). If it makes you both smile, you've found your pair. And if a fabric or a mask stirs you more than you expected, that's a gentle form of fetishism, a good clue for what comes next.

A role-play costume has to last the whole evening, then fall away gracefully. The question to ask yourself: can my partner take it off me unaided, without scissors and without a fit of nervous giggles?

What comes off easily: the cape (which then doubles as a blanket), the lace-up corset your partner unties, the ruffled shirt, the long gloves peeled off finger by finger. What makes everything complicated: catsuits that fasten at the back, latex that clings to the skin, pointed false nails (fearsome when it comes to caresses).

To make the moment when everything falls away last longer, take your cue from the striptease that takes its time, and choose in advance the piece that will stay on: a mask or gloves kept on once the rest has gone, and the character is all the more intoxicating for it.

When it comes to make-up, white sheets are your enemy. Water-based make-up, set with translucent powder, transfers far less than greasepaint. Fake blood stains everything: keep it for the costume, in a washable version, and never on a neck that's going to be kissed. Forget the glitter, test the make-up on your wrist the day before, spread a dark towel over the pillow and keep make-up remover by the bed.

As for vampire fangs, go for small caps that come out in a second: nobody kisses well with ten-centimetre fangs!

How do you suggest role play to your partner? By making the most of the excuse. "For Halloween, how about we dress up and play a little?" goes down far better than a grand declaration about your fantasies. Do it a few days before, over a drink.

Three questions, which each of you asks the other:

• What tempts you about this character?
• What do you really not want?
• How far do you want to go that night?

Limits can be very simple: "no visible love bites, I've got a meeting on Monday", "no jokes about my body". If you're lost for words, see our phrases for saying what you want in bed.

That leaves the safeword. For a first game, the safest thing is for "no" and "stop" to keep their ordinary meaning, even when you're playing prey who resists. The safeword comes on top, like a safety net: a word that has no business in the scene ("pumpkin", for instance) and that stops everything at once, with no argument and no hurt feelings. Some couples add the traffic lights: "green" to carry on, "amber" to slow down, "red" to stop.

How do you do role play as a couple when you've never tried it? By writing less than you'd think. A good scenario fits on a postcard, in three beats. Any more and you'll spend the evening reciting instead of playing.

The beginning: who you are, where you are, what each of you wants. One trait per character, a setting borrowed from your own home (the hallway becomes the drive up to a manor house, the bedroom a remote inn) and the first line, written out word for word: it's the hardest one to improvise.

The tension: whatever stops things moving too fast. Two desires pulling against each other (one wants to come in, the other hesitates), a rule (no touching with your hands) or a clock (it all has to play out before midnight). Without an obstacle there's no story, just a costume.

The open ending: the moment you stop writing, where your bodies take over.

For atmosphere you need very little: a candle, music without lyrics (organ, rain, cello), your phone in another room. Here are three scenarios ready to play.

The beginning. The prey comes home to a flat plunged in darkness, a single candle burning. The vampire is waiting in an armchair and speaks without getting up: "You're late. I hate waiting, and I have waited a very long time."

The tension. It rests on an old rule from the legends: a vampire cannot enter a home without being invited in. Here, the vampire can do nothing at all without an invitation. So the vampire draws near, brushes close without touching, and waits for each permission: "You may come closer." "You may take my hand." "You may... breathe in the scent of my neck." The prey hands out permissions one drop at a time, and in truth, it's the prey who leads the dance.

The open ending. The vampire is finally granted the right to bite: a long kiss on the neck, slow, insistent, sliding down towards the shoulder. What happens next is up to the prey, who can also turn the tables and bite first.

A big advantage for a first try: consent is part of the game. Every gesture is asked for, granted, savoured.

The beginning. The inquisitor, dressed all in black, reads out the charge: "You stand accused of troubling the sleep of the entire village. There is talk of sleepless nights and of neighbours who dream wide awake. What have you to say for yourself?" The witch, sitting on the edge of the bed, smiles and says nothing.

The tension. A single rule: the inquisitor must never meet the witch's eyes, because that's how she casts her spells. Every time he gives in, she wins a spell, in other words an order he has to carry out ("take off your glove", "come closer", "on your knees", "close your eyes"). The more he looks at her, the more he loses his grip, and the more she enjoys herself.

The open ending. The interrogation turns on its head: soon it's the inquisitor confessing, and what he confesses are his own desires. The witch then pronounces sentence... unless he can hold out long enough without looking at her to turn the trial around.

The pair can be swapped round at will (a warlock and a female inquisitor, two witches). What drives it is still power changing sides, and it goes down very well with those who usually always take the initiative, or never do.

The beginning. Two strangers cross paths at a masked ball, at home or at a real party. Golden rule: neither of you knows the other. You keep things formal, you invent a first name, a job, a life. A possible first line: "I don't believe we've been introduced. Are you waiting for someone?"

The tension. The masks don't come off, not yet. Each of you tries to seduce this stranger who, deep down, knows every one of your weak spots (that's the whole spice of the exercise). Compliments allowed, real information forbidden. To raise the stakes, one of you wears a moretta, the small black Venetian mask once held in place by a button gripped between the teeth: no talking possible, you seduce with your eyes and your hands.

The open ending. Whoever takes off the other's mask brings the ball to an end, and the rest is played unmasked... or not.

It's the gentlest of the three, and shy people will especially like it: no power struggle, just the pleasure of seducing your partner all over again as on the very first night.

A costume party is a fantastic playground, as long as you go in with a plan. The most exciting option: split up the moment you're through the door and act as if you've never met. You watch each other from a distance, cross paths at the bar, swap a few words in character, then each go your own way again.

This game of glances is surprisingly powerful. Watching your partner turn heads in their costume, then come back to you with a knowing look, wakes up a desire that dozes off quickly in a settled couple. It's the same mechanism as reviving desire when routine sets in: a little distance, a little of the unexpected.

Agree on a signal for leaving ("I hear the moon is full", a glove slipped off), then don't step out of character again. The journey home is part of the scene, and the doorstep is the perfect moment for the first line.

And finally, drink sensibly: one glass makes the character bolder, three too many make you forget your lines, your limits and the safeword.

What should you do if you laugh during role play? Laugh. Contrary to what you might think, a fit of giggles isn't a failure, it's proof that you're at ease with each other. A cape caught in the door, a Transylvanian accent that slips: it would be surprising if it all went off without a single burst of laughter.

There are three ways back into the game. Let the laughter pass, then pick up the last line a tone lower. Work the mishap into the scene ("You dare laugh at a vampire?"). Or take a real break (a glass of water, a kiss) and start again from the first line.

Sometimes the character doesn't come back, and that's fine too: you finish the night as yourselves, and the costume will have done its job, it will have brought you closer. A laugh shared in bed is worth more than a perfect scene played without believing in it.

The only laughter that's a problem is the kind that mocks the other person (their body, their desire, the way they play). That kind damages trust, and it deserves a sincere apology, out of character.

When the game stops, take the time to become yourselves again, together. Take off each other's make-up (a surprisingly tender gesture after a night of fangs and spells), drink a big glass of water. If the evening began with a Halloween dinner for two, now's the time to finish dessert.

This coming back to yourselves matters, especially when the roles were strong ones (dominating, resisting, being hunted). A few words are enough: "you were incredible", "I loved it when you...", "are you OK?" The characters stay in the cloakroom.

The real debrief happens the next day, over a coffee: what you liked, what bothered you, even slightly, and the character you'd like to try next time. A role play that worked has no reason to wait until the following 31 October to come back.

In short: two costumes that play off each other and come off easily, a conversation beforehand, three lines of scenario, a safeword and plenty of indulgence for your fits of giggles. With all that, Halloween night truly becomes yours.