I try to banish the inappropriate thoughts about my son’s new girlfriend, but they won't fade.

As the week since their visit drags on, I find myself progressively more distracted, both at home and work. On Wednesday I was daydreaming while making sandwiches and then couldn't find my keys. Turns out I put them in the fridge. That'll teach me to fantasize about pulling her over my knee and spanking some sense into her.

I keep telling myself it’s wrong:

It’s just an infatuation. There's probably nothing to it. Wishful thinking. She can't possibly want me: I'm too old for her. Maybe that electric pink hair has clouded common sense. Maybe the fleeting touches and loaded looks are innocent and my overactive libido amplifies them. The visions will fade. The visions will fade.

But they don’t. The daydreams continue. I’d randomly harden imagining her bent over and letting me bury my tongue in her tiny snatch, or letting me use her mouth until she begged to choke on my cum.

If there’s such a thing as hell, I have an all-access pass.

Astrid and I fucked twice during the week, which was probably the most we had done in six months. She was surprised with my voracious horniness but didn't complain at being ravaged. The spark in our marriage had reignited and, honestly, I thought it might take the edge off the treacherous teenage fantasies. But it didn't. As I drilled her against the bedroom wall and called her filthy names, my wife had no idea that it was Molly's sweet face etched with rapturous need, and her open-mouthed whimpers of encouragement, that filled my head.

We invited them to stay for the weekend while they were back in town from uni. Being a glorious Saturday, we took a leafy walk through local Denton Park. It didn't help my state of arousal that Molly wore practically nothing but scraps of cloth that would have made Adam and Eve seem overdressed. Talk about a second skin.

She and Aaron walked ahead of us, hand in hand, and if I thought the way she swung her hips was an exercise in teasing, she then spent the remainder of the day parading around our house in a puny pair of lycra shorts and a black T-shirt depicting some metal band called Avenged Sevenfold. Pretty sure she wasn't wearing panties either. When she bent over to pick up a teaspoon that she’d fumbled—probably on purpose because she knew I wouldn't resist a gawp—I could almost taste the imprint her pussy lips left on the fabric.

Worse, that act fuelled memories of her stifled gasps drifting down the corridor as they had sex in the adjacent guest room the night before. She had clearly been trying to keep quiet and Aaron had shushed her on a number of occasions, but my mind strayed to their room.

Was she on top of him, bouncing as he pawed and pinched her bountiful tits? Did he have his face buried between that tantalizing thigh gap, feasting on her slick little pussy? When her mewls muted, did he have his hand clamped over her mouth, their faces inches apart, or was her tight snatch being ploughed on all fours as she moaned into the pillow?

By the time she cooed into the night she was cumming and her breathing pattern stabilised, I was harder than I could ever recall. I smeared pre-cum with my thumb and jacked myself in the darkness, replaying their coupling, as Astrid snored gently by my side.

Edging myself, unchecked thoughts of Molly’s nubile frame grinding on my cock filled every corner of my mind. I imagined the way her shock of pink hair would sway and brush her breasts as her slender hips circled. The way her mouth would fall open when I tracked whispery touches on buttery skin from the cute belly piercing down to the hump of her mound. And how she would breathlessly urge me to thumb her clit at the junction of my cock sawing in and out of her stretched, teenage heat.

My dick swelled in my grip and I let go to prolong the edge, gnashing my teeth and fluttering fingertips up both sides. I froze when Astrid stirred and turned over, brushing my hip. Her hand slid up my chest and she let out a contented sigh. Never one to let an opportunity go to waste, I stroked the back of her hand then guided it down to encase my throbbing member.

“Mmmm,” she sleepily murmured. “That feels nice.”

“It does.”

“Is it all for me again?”

“Of course.”

She stroked my length and swooped a thumb over the tip. “You’ve started without me.”

“Didn’t want to disturb you.”

There was a lengthy pause before her leg slithered up and over me, and she eased herself on top, her lips skimming mine. We kissed as she rocked her panty-covered slit across my cock.

My breath caught. “Careful. I’m close.”

She sat up, still straddling me, the duvet falling away to leave her silhouette against the moonlight that bled past the curtains. Her warm hands left my chest and caught the hem of her nightie, lifting and depositing it alongside us. Her breasts hung and I slid to cup them, taking their weight and squeezing.

“Ohhh, yeah.”

Increasing pressure, I thumbed her nipples and she moaned appreciation. Hissed when I pinched them, grinding her panties against my stiffness. The firm pebbles atop her breasts deformed further in my grip and she gasped. “Fuck that's making me wet.”

The truth of that statement joined the slick pre-cum oozing from the head of my stalk, our arousal staining her underwear inside and out. I grabbed for her hips and hoisted her clear of my cock, fighting the bubbling urge to cum.

She slid her fingers down beneath the elastic of her panties and groaned when she made contact with the wet jewel inside. The rumbling, throaty moan didn't help my need fade, but I somehow held back, sharing her rising pleasure as the material whispered against the back of her hand.

“Astrid Tanning, you're so beautiful.” Her sighs deepened, finger circling in the darkness. Remembering how she responded the week before, I added, “But sometimes you can be such a needy little slut.”

“Ohhhfuck,” she breathed, the syllables catching and dying in her throat.

My fingertips dug into her hip and I eased her towards me. “I have to taste you. Smother me with your hot pussy. Make me eat you.”

She shuffled, the insistent beat of her masturbation growing louder until her wet panties hovered an inch above my mouth.

“Yeah, that's it. Be my dirty girl. Show me how much you need to be fucked.”

I breathed in. Savoured the scent. Tugged her to meet my lips and smeared her juices across them. She ground against my nose and cheeks, exhaling noisily.

Her bouquet was intoxicating. As I devoured the fabric and its slick contents, alternately lashing my tongue and nibbling her sweet slit through her soaked panties, a soft chant rose. “Yess take me. I'm your little whore. Your filthy little whore.”

She ground harder and I snarled into her snatch, gripping her hips tightly. Rocked my face and gnawed her concealed flesh, unable to speak even if I wanted to.

“Yess, eat your naughty slut. Ffuuck.”

I didn't let up until she stiffened and groaned into the veiled darkness that she was cumming. Her juices leached through the fabric, permeating onto my hungry tongue and I lapped over and over as she mewled. Unless Aaron and Molly had fallen asleep promptly after their own session, they couldn't fail to hear us. I wondered what Molly thought of our antics, and whether she would piece together the fact I'd been listening to her.

My cock was still ramrod hard and as Astrid’s breathing slowed, I dragged her down my body towards it. Pulling her knickers aside, I nudged her wet entrance then plunged inside. We both gasped and I began to piston in and out of her. No time for delays, we went at it, me supporting and squeezing her tits as she bounced and rotated her hips. Rhythmic groans rang out and she became more vocal on the back of them. “Yeah. Mmm. Fuck me. Fuck me. Fuck my slutty cunt with your huge dick.”

Her tirade of filthy talk and the tightness of her silky pussy elevated my own breathing until I cursed as I erupted inside her. She flopped onto me and whispered she was cumming again too, and we lay there, quivering and pulsing and then recovering, hearts hammering against one another.

I swear there was a giggle from the room next door and some further creaking of the bed, but sleep began to take its toll and I drifted off with Astrid in my arms. She'll never know how close I was to calling out Molly's name by mistake, my mind playing tricks on me in the dark.

I'm doomed, for sure.

After the walk and a light lunch, we play some silly card games and then I settle in the armchair with a beer to read the latest Lee Child while my son and Molly disappear upstairs. Astrid graciously agrees to prep dinner instead of her usual routine of yoga in our bedroom. Perhaps she wants to give the youngsters some space.

Jack Reacher cracks skulls as usual, and even as the beer flows and urge to pee rises, just one more chapter wins until I can't ignore it any longer. I put the book down, scurry upstairs to the bathroom, burst in and freeze.

Molly, her back to me. Naked except for a black bra over which her pink mane tumbles, one leg propped on the toilet, attention on her privates. She snaps her head around and our eyes meet for the briefest moment before I lower my gaze to the floor, maybe lingering at her flawless bum en route. “Oh God, sorry.”

Backing out of the room, I shut the door and hop from foot to foot, trying to ignore the urge to wee.

The door opens a crack and she peeps out. “Forgot to lock it, oops.” She eyes my discomfort. “You'd better take care of that.”

Swinging the door open, she steps aside, now wrapped in a bath towel that ends maybe an inch below the peachy cheeks still imprinted on my mind. I don't move, waiting for her to leave, and she giggles. “Come on. I won't look.”

I give in, hustling past her, the door clicking shut behind me as I lift the seat and scrabble to free my cock. The sigh of relief is involuntary.

After I finish and flush and zip up, I turn for the sink. Gawp. She'd unhooked her bra and let the towel fall, both pooling around her ankles.

“Molly…” I whisper.

“Andrew,” she whispers back.

I try to look away from her nakedness but she’s magnetic. Beautiful. Aside from the belly piercing and a few freckles dotted across her upper chest like echoes of the ones dusting her nose and cheeks, she’s milky smooth and unblemished. She tips her head slightly to one side and continues in a hushed tone. “I have a question.”

“Molly, I don't think this is appropriate. You… my wife is... y’know, Aaron, I…”

“It's about Aaron.”

“Oh.”

“Well, two questions really.”

I step to the sink and rinse my hands, noting that it’s full of soapy water and a razor is resting near the hot tap. Reaching for the hand towel, I catch sight of her in the mirror and our eyes lock. Mostly. I might have strayed to take in her buxom boobs and the darker circles of her areola that surround the peaks. I swear her nipples have firmed.

She smiles at my struggle. “It's okay to look. I'm not shy.”

“Clearly.”

Taking one step closer, she whispers, “I was going to surprise Aaron tonight by shaving for him. But it's difficult to know if I've missed a spot. Would you—” she pauses and gives a coquettish giggle, “be able to check?”

I straighten the towel on the rail. “That's not appropriate.”

“Please, Andrew,” she breathes, taking one step closer. “You want me to be my best for your son, don't you?”

“Well, I—”

“Pleassse,” she sing-songs, taking the final step to invade my space until our hips are almost touching. “I'm nearly done. It'll only take a minute.”

“You're not… finished?” I swallow.

Reaching past me, her arm grazing my side, she retrieves the razor. “Almost.”

I move aside and she returns to the toilet where she'd been when I first came in. She turns her head and throws me a cheeky grin. “You should put the seat down. It's polite when there are ladies present. Especially guests.”

She lowers the lid, bending a little and I gibber. “I normally do. I was, y'know.”

“What? Distracted?”

“Yes,” I hiss. “That's one word for it.”

Turning and perching on the lid, she leans back. Inches her feet apart and I lick my dry lips as hers splay. My god she has the prettiest slit. One half is devoid of hair, the other has a few stray wisps that she strokes away with the blade.

Her stance widens and there’s definite moisture dappling her entrance, glimmering in the sunlight cast through the bathroom window. She offers the razor. “Rinse, please.”

I take it. Swirl it in the sink water and hand it back. Our fingertips brush and a jolt of electricity surges through me. My cock swells.

The scrape of the blade is the only sound, bar the birdsong filtering through the ajar top pane of the window. I’m holding my breath.

“How am I doing?”

I find my voice, brittle and quiet. “Good.”

She notices my furtive glance towards the door and whispers, “Don’t worry. I locked it this time.”

Fuck, is that better or worse?

Changing angle, she scrapes from the tender lip outward, covering her slit with a finger of the other hand. When she passes me the razor to rinse again, her fingertip glistens. I sluice the razor and offer it back.

“Actually,” she bites her lip, “I'm going to struggle to do the next bit.” Her eyes bore into mine. “Would you do it?”

“I… I. No, I can't, it's—”

“Not appropriate, yeah, I know. But it'll be quicker.”

“Molly. Don't.”

She rises. Turns. Bends at the waist and slithers her hands back to part her cheeks. I nearly drop the razor. “Please, Andrew,” she purrs. “I want to be super smooth for Aaron when I tell him to lick me there.” As if I'm not speechless enough, she gives a wiggle. “Just a few strokes.”

I stare, mesmerised at her delicious behind with its mouthwatering, crinkled rosebud framed by her fingertips, nestled above the freshly shaved pink lips. “Strokes,” I grumble. “I oughta spank you.”

She lets out a curious squeak. “Oh, that would be wholly appropriate, don't you think? I've been so naughty.”

Despite the knowledge that what I’m about to do crosses more lines than there are in a UN peace agreement, I step forward. Bend for a closer look and cover one of her wrists with my palm to steady her.

Be quick. Get it over with. But oh how I want to take my time.

Dammit.

Her breathing stutters and I offer the razor to her crack, swiping downward, following the inner curve of one cheek in a long, smooth stroke. A stray droplet of water continues to trickle a path over her bare pussy lips, dripping to the floor between her feet.

I raise the blade and repeat the other side as she exhales. “Thank you so much. I really appreciate this.”

My own breathing is laboured. Her arousal drifts and it’s driving my dick crazy. “Hold still.”

Moving the razor up into the faint crease below her sacrum, I glide down, the left edge of the blade scuffing her exposed asshole. With one more stroke, the right edge this time, she’s completely hairless from the eyebrows down.

Rinsing the blade, I empty the sink and swirl it clean while she lets go and runs a fingertip over her crease. “Ooh, that's perfect, thank you. How do I look?”

“Is that the second question?”

Turning and standing, she tracks her gaze down my body, pausing at my obviously straining bulge. “No.”

“Do I want to know what it is?”

“Mmm. You’ve kind of answered it already.”

“Oh, good.”

She barrels on regardless. “Ever since Aaron and I started dating properly, I began to wonder if the, uhhh, size ran in the family.”

I guppy a little. “Why are you doing this, Molly?” I try to sound stern. Firm, like Astrid told me to be with her. But it comes out needy.

She takes her time to swing her attention up my body and find my eyes. “Because I can. Because it excites me. Doesn't it… excite you?”

“Sex? Or… this?”

The faint chuckle that escapes her lips precedes her stepping right into my proximity. So close that her body heat permeates my shirt. “Oh I know sex excites you. How did it go, hmm?” She brings her lips up, breath tickling my ear. “Fuck my slutty cunt with your huge dick, wasn’t it?”

I colour. It’s the first time I've heard her swear and it stabs me in the heart with its power. “Oh. You heard.”

“Mmm-hmm. And you heard us, didn't you Andrew? Naughty boy, listening in as I got,” she lengthens the first character, “fffucked.”

I whimper.

“Did it make you hard hearing my moans when he pumped his huge dick inside this sweet, innocent little,” she pauses and enunciates a perfect strut vowel, “cunt?”

I swear she flashes her tongue across my ear lobe but it could have been her lips or hot breath as she continues to whisper. “And how about when he stretched me as he pounded me into the mattress or licked me and I begged for more? Did you touch yourself at the thought of me riding his face? Clutching the back of his head as I rocked my hips against him and came in his mouth? Did you?”

My voice is tiny. “Yes.”

“Mmm. You woke your wife and fucked her, didn't you? Ate her until she begged. I heard everything.” She pauses and my cock rages in my jeans. “Tell me, Andrew, were you thinking of her the whole time, or,” she skims the back of her hand against...