It was marriage second time around for both Frank and Yvonne, and in truth they were best friends with benefits, rather than being in love. But they had been together for four years, and the relationship worked; as well as having loads in common, he earned really good money – more than Yvonne’s first husband ever had, so she was happy with her vastly-improved lifestyle, and she was a great cook, which was important to Frank, as he couldn’t cook toast! They were faithful to each other and had a moderately active sex life, so overall, it was a successful relationship.

Yvonne’s seventeen-year-old daughter, Gillian – or Jilly as she preferred to be called – still lived with them. She was a typically cute thirteen-year-old when Yvonne and Frank first met, and Frank had taken to her immediately, even though she had apparently gone off the rails in a major way after her father had walked out, and it took a good couple of years for to settle down. She had recently taken to calling him ‘Dad’ instead of Frank, and he was secretly pleased, hoping he was having a positive influence on her.

He was also very aware that she had grown from a girl into a woman while he had been with Yvonne. She was pretty and curvy in a way that he was struggling to ignore. Although she was an adult now, she was Yvonne’s daughter, and young enough to be his own. As if that wasn’t enough to keep him at bay, he was also sure that she would be totally grossed out if ever did come on to her. It didn’t stop him fantasising about her when he was having sex with Yvonne though, and he was almost sure that Jilly sometimes flirted with him, but he never took it seriously.

One night, when Yvonne was on night-shift, he went to bed early to watch football in bed. It was a treat he could only enjoy when Yvonne was out. Jilly had been in her room all evening. While he was watching the game, he heard Jilly’s door open, and then a knock on his door. He thought he heard her sniff. He slept naked, so he checked he was covered up before inviting her in.

She almost burst into the room and leapt onto the bed, cuddling into him, in tears. She was wearing a tight white tee shirt with no bra, and pink knickers. She had decent-sized breasts and her nipples were pressing against the fabric of her shirt. Her long blonde hair was tied in bunches above her ears. He entertained a fleeting crude thought about her, and then silently reprimanded himself for thinking that way when she was clearly distressed.

When he asked her what was wrong she explained that she had been watching a horror movie, and it had terrified her. She asked if she could sleep in his bed for the night. She was too frightened to go back to her own room. He hesitated, and she apparently took that as a ‘yes’ as she slid straight beneath the quilt with her head on his chest and an arm around his waist, squeezing tight.

He felt he had no choice but to let her cuddle in to him; he would feel awful sending her back to her room in that state, so he just sighed in submission, put an arm around her shoulder, and carried on watching the game, hoping that would distract him from thoughts he shouldn’t be thinking. It seemed to work.

He felt her relax, and her breathing fell into a light, steady rhythm. He didn’t realise her arm had moved until he felt her fingers touch his pubic hair. He froze. Had she done it intentionally? How should he stop her without hurting her feelings? What if it was unintentional and she was just falling asleep? Suggesting she was deliberately behaving inappropriately when she wasn’t would horrify her.

He waited, trying to convince himself it was innocent. Her breathing was slow and shallow. She was asleep, wasn’t she? She stirred like she was half-asleep and just getting comfortable, but then her hand moved down onto his cock. He didn’t dare move. He listened to her breathing. She was asleep, wasn’t she? She didn’t move again, and her breathing stayed light and slow.

He realised he was breathing more deeply now, and he could feel his heart beating faster. She was a beautiful, sexy, half-naked young woman, and her hand was touching his cock. He wanted her but knew it was wrong. She was his step-daughter, and he had a parental responsibility towards her. He should not be thinking about her firm young body pressed up against him, or her fingers resting so lightly on his cock.

Despite himself, he felt his cock swell a little beneath her hand. Then a little more. He was willing himself to stop. Too late. He was getting an unstoppable erection. He was suddenly aware of her fingers curling around his cock and gently massaging it, and it immediately stiffened even more.

“Jilly. No. You mustn’t,” he whispered, but she massaged a little more firmly and he groaned as his cock rapidly became fully erect. She was masturbating him properly now, but still beneath the quilt. She released him for a moment, pushing the quilt away to expose him, and his erection slapped against his stomach. She took him in hand again, continuing to masturbate him as quickly as she could. He was conscious of the fact that her head was still on his chest, with her face just inches from the tip of his iron-hard cock.

He thought his head was going to explode – his mind was screaming at him to stop this immediately, but his cock was begging for more.

Then Jilly spoke, her voice strangely young and girly-sounding. “You’ve got such a big willy, Daddy. Can I suck it?”

He was stunned. Before he could react, she took him in her mouth, her head bobbing rhythmically. She had gone seriously off the rails when she was younger, judging from her amazing blowjob skills. He groaned with pleasure at the delicious sensations of her soft lips and wet tongue caressing the swollen head of his cock, and knew that he was beyond stopping her now.

She rolled over so that she was lying on his legs, gazing up at him with big round innocent eyes as she continued to suck him, her bunches swaying rhythmically. He was amazed he didn’t cum in her mouth instantly.

After a couple of minutes, she stopped, but held his gaze, as she slowly raised up onto her knees. She peeled off her tee-shirt, then stood straddling his legs and removed her knickers. She was shaved. He didn’t dare move. He just stared up at her as she began to massage her breasts. She let one hand wandered down between her legs, and she licked her lips provocatively as she slid a finger inside herself.

She giggled. “Ooh Daddy!” That impossibly sexy, girly voice again. “You’ve made me so wet!” Another giggle. “Does Daddy want to play with Jilly’s titties? I bet he does!”

She dropped to her knees, kneeling astride his thighs, and reached for his hands, pulling them up to her breasts. They were warm and firm, and her neat, pink little nipples stiffened with arousal at his tender touch. She was stroking his cock again.

She leaned forward until she was almost nose to nose with him, gazing into his eyes. as he gently squeezed her breasts. “Jilly wants to play ponies, and ride on Daddy’s big stiff willy,” she whispered playfully, and swiftly lowered herself straight down onto him. He groaned aloud as his whole length slid deep inside her, and she began to writhe back and forth, grinding herself off against him.

His mind was a hurricane of thoughts: this was so wrong but the feeling of her tight wet pussy gliding up and down his hard shaft was exquisite; he was the adult here and should immediately take control and stop her, but letting her stay in charge and use him for her own gratification was too big a turn-on; he was committing adultery and felt guilty but didn’t want it to stop; this was probably incest and illegal, but he couldn’t take his eyes off her beautiful body and desperately wanted to cum inside her as her tight young pussy muscles continued to rhythmically stimulate his rigid cock.

She was extraordinarily athletic and rode him at a phenomenal pace, grinding her young clit against him until she came, long, hard and loud. She leaned forward and kissed him on the lips for the first time, hard and passionate, and he responded, his hands roaming all over her lithe young body.

She broke away, fluttered her eyelashes, her head cocked to one side. “Does Daddy want a ride on Jilly, now?” He nodded. “Yes, I do,” he breathed.

She rolled off him and onto her back, with her knees up near her chest, fully exposing her pussy to him with its delicate lips parted and waiting for him, still slick from her orgasm. He couldn’t resist feasting on her, probing her deeply with his tongue and teasing her clit with rapid flicks and gentle sucks. She gasped, moaned and bucked, pushing her hips up to meet his face. He ran his tongue down the full length of her cleft, from clit to anus, the tip of his tongue massaging the tight little rosebud for a few moments before returning to her clit, sucking it until she squealed and gasped and came again.

He lapped her juices from her and then tenderly kissed his way up her stomach to her young breasts. He sucked each nipple before kissing her on the lips. She could taste herself on him and yearned for him to fuck her. Gazing into her eyes he pushed himself deep inside her in one swift easy thrust. “Ooh Daddy! What a big hard willy you’ve got!” she squealed, as he penetrated her. “Ride me hard, Daddy. Ride me as fast as you can!”

He didn’t need a second invitation and began ramming her as hard and as fast as he could. She loved it and yelled her girly encouragement. “Fuck me, Daddy! Fuck me harder. Cum in me, Daddy. Cum in your little girl. Squirt your cum in me!”

She was scrambling his brain. All this ‘Daddy’ business was freaking him out. It felt so wrong, and yet it was so incredibly sexy. He rammed her for all he was worth, squeezing her young breasts firmly, and feeling his balls slapping against her teenage ass until he just couldn’t hold off any longer.

She sensed he was on the edge. “Cum in me, Daddy! Squirt in my pussy!”

That blew his mind, and as he came in her he yelled “Oh god, Jilly! Daddy’s cumming in you! Daddy’s cumming in his little girl’s pussy!”

As soon as he was done, they collapsed in fits of laughter. He had to ask. “What’s all this girly ‘Daddy’ business, anyway?”

She grinned at him. “Because I was only thirteen when I first realised I wanted to fuck you. I’ve been gagging for it ever since! That’s why I put my hair in bunches, as if I was thirteen again.” That made them laugh again. “And I hadn’t been watching a horror film. I fibbed. I’d been watching porn, and it got me so horny I had to find a way to come and fuck you.”

“Well, I guess it worked!”

They laid together recovering for a while, and then he turned to her.

“What have we done, Jilly? This is wrong.”

She looked back at him. “Yeah, but we’ve both wanted to do for a long time. Right?”

He nodded and sighed. “I guess.”

“It doesn’t have to stop here, does it? I know it was as good for you as it was for me. Anytime I want you, I’ll let you know by casually slipping ‘Daddy’ into the conversation. Mum’s already used to me calling you ‘Dad’ now, so she won’t notice.”

“And how do I let you know that I want you?”

She laughed. “Oh, I’ve always known what you’re thinking about me from the way you look at me. Trust me, I’ll know when you want to fuck your little girl, Dad.”