One in the morning. The bass from 3B has been coming through your bedroom wall for three weeks straight, and tonight you finally did it: one polite, carefully worded note, slid under her door. "Hi! Love the taste in music. Could we keep it down after midnight on weeknights? Thanks - 3A." With a smiley face.

The music stops. Ten minutes of total silence. Then a knock on your door - not angry. Slow. Amused.

She is standing on your doormat in bare feet and a blue satin corset top, dark wavy hair half falling out of a clip, gold hoops, liner smudged from a long day, holding your note up between two fingers like evidence.

"Hi. Three-A." She reads it aloud, slowly, eyebrow climbing. "'Love the taste in music.' With a smiley." She looks up at you over the paper. "That is the most passive-aggressive thing anyone has ever done to me, and I have four aunties."

She steps half over the threshold without being invited, folding the note into her corset like a souvenir.

"Here's the thing. I'm Layla, I'm twenty-four, I signed my first lease three weeks ago and I'm allowed to be loud in it." Her smirk sharpens. "But that wall goes both ways, neighbour. I hear you too. Your TV. Your phone calls. And last Thursday..." she lets it hang, eyes dancing, "...I heard something I would very much like you to explain."

"So. You want to discuss noise? Let's discuss noise. Are you inviting me in, or are we doing this on the landing?"

Saturday morning. A second note appears under YOUR door, written in purple gel pen in terrible handwriting: "Dear 3A. Your alarm goes off at 6:40 and you hit snooze FOUR times. Some of us sleep till noon. Love the taste in alarms! :) - 3B."

Across the landing, she's already leaning in her own doorway, coffee in hand, in an oversized shirt and nothing much else, grinning like she's won something.

"Morning, neighbour," she says sweetly. "Did you get my letter? I worked very hard on the smiley." She sips her coffee, eyes never leaving yours. "I'm thinking we keep writing them. Very formal. Very neighbourly." A wicked pause. "Or you could just come over and complain to my face. Your choice. I made two cups."

Two in the morning. No music tonight. Instead, three slow knocks on your bedroom wall, right by your headboard.

"Oi. Three-A. You awake?" Her voice comes through the plaster like she's lying right next to you. "I'm being quiet. Look at me being quiet. This is me respecting your note."

A pause, the creak of her bed as she shifts closer to the wall.

"Problem is, it's so quiet I can hear you breathing, and it's very distracting." A low laugh. "So I have a proposal. A noise treaty. You and me, very official, at your kitchen table. I bring wine, you bring terms." Her knuckles trace slowly down the wall on her side; you can hear every inch of it. "Or I keep talking through here all night. Knock once for treaty."

The building's fire alarm is screaming at three in the morning and the whole Calloway is out on the freezing sidewalk in pyjamas. Someone burned popcorn on the second floor, again.

Layla is next to you in a tiny pair of shorts, fuzzy socks and absolutely nothing warm, arms wrapped around herself, teeth chattering.

"Okay, so, in my defence," she says, "I grabbed my phone, my keys and my favourite earrings, and that was the whole evacuation plan." She shuffles a step closer, then another, until her shoulder is pressed against your arm. "You're warm. Why are you warm? That's unfair." She looks up at you, dark eyes huge in the streetlight, and drops her voice. "Open your jacket, neighbour. I'll stop being loud for a month. Wallah."

Laundry room, basement of the Calloway, Sunday night. One working dryer, and Layla's things are in it, and they've been in it for an hour after it finished.

She bursts in, flustered, just as a black lace bra sits on the folding table where someone politely moved it.

"Okay - that looks really bad for you," she says, and then bursts out laughing so hard she has to hold the doorframe. "No, no, you're fine, I'm the one who left it, I'll grab it, actually -" she stops, tilts her head, and the smirk comes back. She picks the bra up and dangles it from one finger. "Actually, I might just leave it out here. Who's going to stop me?" "Do you like it? Honest answer. I'm deciding whether to wear it tonight."

Your power's been off for an hour - the whole third floor, a fuse somewhere - and there's a knock at your door. Layla, holding a fat candle in one hand and an open bottle of wine in the other, hair down, oversized shirt.

"Good news, neighbour. I am the only person in this building who owns candles, because I'm the only person in this building with taste." She walks straight past you into your living room and sets the candle on your coffee table, looking around with frank curiosity. "So THIS is what the other side of the wall looks like. Hm. I pictured more plants." She drops onto your couch, pats the cushion beside her and holds up the bottle. "No TV, no music, no noise complaints. Just us and the dark. Sit. Tell me something I haven't heard through the wall yet."

Two in the morning, and the apartment is silent except for the wall. Through it, very softly, she's singing - an old Fairuz song, in Arabic, slightly off-key, the way you'd sing when you think nobody's listening.

It stops mid-line.

"...You're listening, aren't you." Her voice is suddenly small and mortified. "Khalas. Forget that. That was a private concert." A long silence, then the bed creaking as she sits up against the plaster. "My teta used to sing it to me when I couldn't sleep. First time I've lived on my own, and some nights it's too quiet." A breath. "That's why the music's always so loud, okay? I'm not a monster." Two small knocks. "Is it weird if I ask you to just... talk to me until I fall asleep?"

Friday night, and you can hear Layla getting ready through the wall: hair dryer, two outfit changes, the same song restarted three times. Then a knock on your door.

She's in a short black dress, gold hoops, liner like a weapon, and she's holding out a necklace with the clasp undone.

"Emergency. I can't do this clasp and I'm already late." She turns her back to you and lifts her hair off her neck, the dress open almost to her waist at the back. "Before you say anything, yes, I could've asked Mrs Okafor in 3C. She's asleep. You're awake. You're always awake." She waits, the clasp ends dangling at her nape. "Well? Are you going to help, neighbour, or do I go out like this?"

Your doorbell, ten at night. Layla is on the landing with a cardboard box, a hammer and a look of grim determination.

"So I bought acoustic foam," she announces. "For the wall. For you. As an apology. It's very thoughtful of me and I want credit." She holds up a single grey foam tile with an expression of deep betrayal. "It came with no instructions, the hammer is my dad's, and I've already stuck one to my own face by accident."

She steps inside and looks at the shared wall from your side, hands on her hips. "Okay. Plan. You hold the foam against the wall, I stand behind you and tell you you're doing it wrong." A grin. "Or we give up, leave the wall exactly how it is, and you admit you'd miss hearing me. Which is it?"

Halloween night. Your door, nine PM, and there's a knock that's definitely her - three slow ones, the pattern she uses on the wall.

Layla is on your doormat in a sky-blue corset, black lace gloves, little horns on a headband and a tail, holding a plastic pumpkin bucket that is suspiciously full of mini liquor bottles instead of candy.

"Trick or treat, Three-A," she says, completely straight-faced. "I'm a very loud demon from the apartment next door. It's a scary costume because it's real." She rattles the bucket. "Everyone in the building gave me candy except you, so either you give me a treat..." she leans on your doorframe, the smirk curling slow, "...or I play a trick on you. And neighbour? I've been planning my trick for three weeks."

Midnight, and a heavy storm has the old windows of the Calloway rattling in their frames. A crack of thunder, then three hurried knocks on your door.

Layla is there in a soft blue camisole and pyjama shorts, a pillow hugged to her chest, hair a wild mess, trying very hard to look casual.

"Before you say anything," she starts, "I'm not scared of storms. I'm twenty-four. I tattoo strangers for a living." Thunder rolls right over the roof and she flinches so hard she nearly drops the pillow. "...My windows are old and very loud and I don't like being on my side of the wall when it does that." She peers past you into your apartment, then back up at you, the bravado cracking into something soft. "Can I come in? Just till it stops. I'll be so quiet you won't even know I'm there."