Late in the evening, Aria and I have just finished watching some kid's movie cuddled together on the couch. In the middle of summer I don’t have to worry about her and school, and I'm off work tomorrow. 
She yawns exhaustedly, and looks up at me in her pink nightgown with sleepy eyes. I fluff her hair.
"Are you ready for bed, Aria?" I ask her.
"I guess," she answers, "But I don't know if I'll be able to sleep so good after the movie. Can I have some of your special warm milk?"
"Absolutely, honey. One minute, you stay right here." I answer, before slipping off the couch and heading into the kitchen. When she asks for special milk I know I'm going to have a very good night as well, and even thinking on that makes my cock grow hard inside my panties, tenting my skirt as I head around the kitchen wall out of sight of my daughter.
In the kitchen, I pour some milk into a saucepan to warm, and get a cup out. I check over my shoulder to make sure Aria is still in the living room before I lift my skirt enough to free my cock from it's confines. As quietly as I can I slowly begin stroking myself, trying to work myself up without too much noise. After a few minutes of intense rubbing, I'm close to cumming. I still my breathing, and strain to hear any sound from the living room, but thankfully there is none. 
Finally just as the milk begins to simmer, I let loose into the cup I'd set out for my daughter, a stream of cum spraying into the bottom of it and quickly filling it up halfway. I manage to squeeze my cock long enough to redirect the rest of it into the sink nearby, the sound of it surprisingly loud.  With a final pulse of my cock, I grab the cup and pour the warmed milk into it, stirring with a spoon to mix my semen into it. It blends well, the shift in color barely noticeable. I tuck my cock back into my lacy panties before finally pulling down a bottle from an upper shelf and eyedroping a little extra liquid into the mix.
Taking the warm mug, I head into the living room. Aria's still sitting on the couch, looking like she's about to nod off. The creamy white fur of her thighs are visible where her nightshirt has ridden up.
"Here's your milk, honeybun." I say to my daughter as I hand her the mug full of my own cum and milk, unknown to her. I sit down next to her on the couch, and she perks up immediately, drinking the warm liquid and gulping it down.
"That's so good, mom. I love drinking your milk," she says, and my cock stiffens slightly at this. She's so adorable, so innocent. I hope she'll be that way for a long time. 
"Do you want some more?" I ask her, "Or do you want to go to bed?"
"I'm sleepy, I'm ready for bed now." She rubs her eyes, and gets up to head for her bedroom.
I get up to follow, turning off the lights in the house as I head back to our bedrooms. Aria has already climbed into bed and pulled her pink blanket up over her. She really does like the color a lot.
I lean in to give her a kiss on the forehead and she mutters sleepily, "I like the dreams I have when you let me have your special milk."
I can smell my own cum on my own daughter's breath, and my cock hardens all the way. Her eyes drift shut before she can spot the bulge in my skirt.
"Goodnight, baby girl. Love you," I whisper to her, and she lets out a contented sigh as she drifts to sleep.
I turn down her bedroom lights to a gentle glow and head back to my own room, where I shed my own clothes and stretch out on the bed to stroke myself to the thought of Aria. I make sure not to cum, instead pacing myself and watching the clock on my side table. 
Half an hour passes this way as I edge myself, repeatedly letting myself subside just before reaching orgasm. Feeling like enough time has passed, I stand up and stretch, my cock bobbing in front of me.
Leaving the lights off, I slip out of my room and cross the hall to walk into my daughter's room. I'm unworried about my nudity, as the dropper of medicine I'd slipped into her milk will keep her asleep through almost anything. I could turn up the lights if I wanted to, but keeping them dimmed feels so much more intimate to me. 
I approach her bed, looking down Aria's sleeping form beneath the blanket. Precum drips slightly from my cock head, and I feel my pussy beneath getting wet thinking about what I'm about to do. I slide my hand under the blanket to stroke her soft fur and feel her sleep, my knuckles brushing lightly against her stomach over her nightshirt.
Thankfully with the sleeping meds, she'll never have to know about this until I choose to show her. Aria can only lose her innocence once, so I'm saving it for a special time.
Grabbing the edge of the blanket, I draw it back and expose my daughter. Her breathing doesn't change, her sleep undisturbed as I take in her nightshirt-clad form, her 8-yo body undeveloped. No visible signs of breasts, no curve of hips yet.  She's perfect, innocent, and yet not as untouched as one might think.
I lean in and kiss her forehead, and she lets out a contented sigh. Despite the sleeping meds she does respond at times, showing me how much she's grown to enjoy our secret nighttime activities. So secret even she doesn't know of them.
Reaching down between her legs, I lift Aria's nightshirt up. It hangs loose on her normally, so it's easy to get high enough to expose all the way up to her stomach, showing the unbroken expanse of white fur. Her panties are pink with a small white bow on the front, and I smile at that. My daughter really is obsessed with pink.
I place a soft kiss on her stomach, and then slide my hand down. My fingertips brush against her pussy through her panties, and she moans in her sleep.
Aria's body was a lot less receptive when I first did this, but with time she's become openly aroused by my touch. Her body has learned to accept her mother's touch, and even anticipate it, judging by how damp her panties are already. 
I suspect she began getting wet as soon as she drank my cum, looking forward to her night's pleasant dreams. I don't think she even notices it happening to herself. She just knows that it feels good, and that she wants more.
I slide my fingers down her panties and into her wetness. "Mmm, you're so ready for me already, baby girl."
Her pussy is a smooth slit, plump lips hiding the delicious inner walls, her clit hiding away. It really doesn't feel large enough to fit even a finger, let alone a full sized adult cock, but I know it does. I know that if I push my fingers in far enough she'd probably cum before I could pull them out. My little girl has developed a hair trigger on orgasms, which only makes it a continued surprise that she sleeps through them.
I slide her panties down and off her legs, feeling the wetness on them as I do. Poor girl is in need. She's lucky her mother is here to give her what she needs.
I slide my fingers into her warm, wet pussy, reveling in the feeling of her arousal, crawling up onto the bed as I do. It's easy to slide her legs apart to get between them, bringing my face in close enough to smell her arousal. I lick her slick slit, tasting her fragrant musk, before I take the time to savor the taste of her juices. Her hips buck slightly in her sleep.
I find her clit with the tip of my tongue and tease it, my two fingers gently gliding through her folds. She moans, her arousal evident by the wetness dripping down my knuckles. I lean in and give her clit a firm lick.
"Mmm, mommy..."
I smile to myself before I return to licking, vigorously working her slit around my hand and giving special attention to her clit. I know my daughter's going to cum very soon, I've felt this before.Experience has taught me to be able to sense these things with Aria, and my cock throbs in anticipation.
I continue to lick and suck on her clit until I feel her tensing up. Aria begins to buck, and I know she's there. I slide two fingers into her and press hard to her g-spot and she spasms even harder, lifting her hips off the bed with the force of her orgasm. It lasts a long minute or so of her twitching with pleasure before settling back down. Through the entire thing she never woke.
I look down at my 8-yo daughter I just brought to a raging orgasm with adoration. She's beautiful, and she's ready for me now.
I place the tip of my foot-long cock at her tiny little slit, wondering that I'd managed to stretch her so well over time. Not only will it fit, but she enjoys every inch of it.
I slide my length slowly into her tight, wet tunnel, enjoying the way she grips me. Aria's prepubescent velvety walls hug every inch of her mother's cock, and demand more.
Knowing this, I give her what she needs. I work my hips, pushing my cock head to the back of her vagina, rubbing past her G-spot again. Aria moans loudly as I drive my cock balls-deep into her.
"So perfect," I purr to myself as I drag myself back out, almost having difficulty freeing myself from my daughter's pussy. A look of bliss is on her sleeping face.
I stop with the head of my cock back at her entrance, and slide it back in as far as it'll go. Sometimes I wish she'd wake up with me buried deep inside her, but it's not time for her to know about this yet.
My thrusts accelerate, the feeling overtaking me. Her body shakes upon the bed, and I push myself down over her to hold my daughter in place as I fuck myself deep into her hole. Aria had her orgasm, in fact has begin to have smaller repeated orgasms simply through her young body experiencing such a thing. It's my turn to finish, to share in that mutual pleasure with my little girl.
"Mmm, aah, fuckkk," I growl, my cock pulsing as I prepare to explode inside her. My knot begins to form, and I grip her hips hard and push. It's a difficult fit, but worth it to tie myself inside my underage daughter. I don't have to worry about pregnancy with her after all.
Forcing it into place, my knot swells inside her pussy, leaving me unable to pull out or do anything but push hard against Aria as my orgasm erupts. My cum sprays out into my daughter's cunt. I lay down on her, my knot throbbing as I settle in and enjoy the feeling of my sperm slowly pumping out. I can feel her twitching under me as she's lost to ecstasy from the feeling of being filled by her mother, from the cock that made her.
I rest on my daughter, my prick still buried deep inside her. I drift in post-orgasm bliss, my knot slowly subsiding, my cum slowly leaking out of my daughter's womb. I hear her murmur gently,
"Love you, mommy..."
Glancing down, I see she's still very much asleep. It must be a fantastic dream.
I caress her hair, smiling. Eventually my cock pops free, and I stand up to look down at my disheveled little girl. 
Aria's hair is mussed, her nightshirt rumpled and pulled up, and her adorable little pussy slowly leaking her mother's cum out onto the bed. 
Obviously I can't have that making a mess, so I pick up her panties and slide them back up her legs. It only takes a little lifting to snug them into place again. They'll catch what drips out. Then, with a long, lingering kiss, I tuck her in and slip out of the room.
Now that I've given my daughter the sweet dreams she expects whenever she has mommy milk before bed, it's time for me to have sweet dreams of my own.
I know that come morning, Aria will be bright and chipper in the afterglow of a night of fantastic sleep and secret sex. 
She's come to expect that somehow the mommy milk dreams make her drip from down below, and doesn't even think twice before cleaning up her own mother's semen from her undeveloped pussy when she has her shower. It's an expected part of the experience.
In fact, one morning peeking in on her I caught her tasting it, and smiling in delight.

It might not be too long before we spend a night together without the milk, after all.