First Time Fantast

© 2025 by KnotYourAverageGuy

I am a FtM trans man, and I have never had a dog fuck me, but I’ve been wanting one to for a while now. I hope to achieve it some time this year, but I doubt it’ll be what I envision in this fantasy. Mainly because my friend (“F”) doesn’t approve of beast sex. But I wish she did, because she had a massive great dane (“GD”), and he’s not neutered. Yet.

Here’s the facts: he’s around two years old, almost full size, and still intact. He’s sexually matured because he’s tried to hump various things of his, but can’t manage to actually mount anything because of his size. And, according to F, whenever he sees me outside the window, he gets very excited. And I don’t just mean energetic. He gets excited. She says it’s gross and I say I agree… but secretly, I don’t. Secretly, it turns me on.

Now, of course, if I were to ever have sex with GD, it would have to be while both F and her partner are out for an extended period of time, guaranteed to not show up unexpectedly early, can’t bring GD with them, and have him alone long enough that they need someone to check in on him and none of their family can do it. This isn’t a likely situation, especially during the pandemic, but I could happen. And here’s how I’d like it to go:

Before heading over, I would gather supplies: towels, a change of underwear, dog treats, and wet wipes. I’d prep myself, using a clit vibrator to get myself wet, then fuck myself with a dildo to prepare myself for him. On my drive over, I’ll keep the dildo still in me, vibrating, to guarantee I’m wet and open. F will have left a key for me, under the door mat, and once I head inside, I’ll be greeted by an excited GD, dancing in his kennel, excited to see me. Hopefully the type of excited he’s been for me in the past.

First, I would take care of his immediate needs: bathroom and a walk. Then, once we’re back inside, I’d set things up in the bathroom while he plays in the living room. Towels on the floor, change of underwear and wet wipes on the counter, and dog treats by the towels. Finally, after all this time, I’ll turn off and remove the dildo, setting it aside next to the dog treats, in case I need to use it later, and head out to the living room.

Once he’s in my sight, I come over to him and begin to pet him, starting with scratching around the base of his tail, before reaching down to stroke the base of his cock. His eager red tip begins to poke out immediately as he thrusts his hips forward, looking back at me with slight confusion. He’s been told “no” so many times when he’s tried humping things. He’s not used to not only being allowed to hump, but encouraged. His ears perk up slightly as he tips his head, before looking underneath him as he watching me stroke his ever-growing member.

I let my pants and underwear fall to the floor, and let him smell my bare sex, before he begins to lick it. His soft, warm tongue slipping between my lower lips makes my knees buckle instinctively as I groan, and begin to stroke him faster, and before long, GD’s cock is erect and ready to breed.

Though I don’t want to, I pull away from his generous tongue and lead him to the bathroom, positioning myself so my lower half is over the towels. I’ve heard and seen how messy it gets once your canine lover pulls out; I’m not risking leaving evidence. I get on my hands and knees, using the tub ledge to prop my upper half up. When GD first approaches, he sniffs and licks my face, and I reach under him and begin to stroke his lengthened cock, and he once again begins to thrust into my hand. Finally, nature begins to take hold, and GD hops up against my back.

He’s big enough and I’m small enough that his paws are on my shoulders as he begins to thrust at my backside, his warm, hard cock sliding against my lower back. He’s completely over me, taller than me, bigger than me, thrusting against me. I reach down, grab him, and help position him right towards my entrance. Once he felt the wetness of my pussy against the tip of his doggy dick, he must’ve known that was where he needed to be, because he thrust forward, just like the overeager teenager he is, and plunged 8.5 inches of hot, virgin dog dick into me.

Now I like size. My favorite toy reaches 7.5 inches deep. But this is a whole inch bigger, and thrusting a lot faster. I can feel his hot cock force itself past my cervix, reaching as deep as it can, treating me no differently than a bitch in heat. GD has me mounted and penetrated, using my wet, dripping pussy to pleasure himself. I can hear the wet sounds behind me as my hungry hole welcomes his large cock. In this moment, I’m not his master’s friend. I’m his bitch, and he plans to make that official as he gyrates his hips in ecstasy, his big paws pinning me down to guarantee he embeds himself deep inside of me. He didn’t know he couldn’t knock me up. His dick didn’t know either. But that didn’t stop him from trying.

Finally, I begin to feel the stretch. The stretch of his knot, swelling inside me, trapping his fully erect length in my cavities, sealing me shut. It stings. I’ve never had anything that large inside of me, but I revel in it, and moan as he continues to thrust sporadically. I can feel his balls twitch, and suddenly, I’m being filled with warmth, the swelling increasing as he has his first orgasm, and its inside me. It’s our first times. I take his sexual virginity, his first fuck, first orgasm, first knot, first breeding session. He takes my dog virginity as his cum spurts into my uterus, filling my womb with his potent seed. In this moment, I’m not a man or a woman — I am a primal beast, a bitch in heat, controlled by nature, by instinct, the need to mate and reproduce. My hole begin to contract as I near my own climax.

I quickly grab the dildo and turn it back on, feeling my pussy hole instinctively flex open the moment I hear it vibrate. Thankfully I can’t open enough for GD to slip out of me, but that doesn’t stop me from clamping my vaginal muscles in an attempt to keep him and his load locked within me. Gently, I slide the dildo between my pussy lips, rocking myself back and forth as I grind against the vibrating shaft. The sensations finally overwhelm me between the pressure on my g spot, GD’s hot doggy cock penetrating my cervix, and my clit being teased; I feel my muscles clamp tightly around GD’s shaft and knot as I cum, each involuntary contraction squeezing his dick, sucking it in, my body demanding he give me all his fertile seed, to impregnate me. My job is to submit to him, be his bitch, and let him use me to breed, to receive his cock and cum and be thankful that he chose me to rear his offspring. My cervix continues to flex around his cock, greedily suckling more cum out of him.

We stay knotted for about 15 more minutes or so, nature’s attempt at letting his sperm soak into me, to guarantee a litter, though that of course won’t be happening, not that either of us care. He has two more orgasms, and I have one more, before his knot finally shrinks enough to pop out of me. I whimper a little as his warm juices leak out of me and down my legs and on to the towels. GD is already heading to the living room to service himself until his erection goes down. I lay, slumped against the tub seat, just taking in what we’d done, knowing it may never happen again.

Finally, I clean myself up with the wet wipes, gather up the towels, change into my clean underwear, and clean of my dildo. I pet and praise GD while I recover my strength, giving him treats to reward him for an amazing first time. I stay with him another hour before getting him back in his kennel, and heading back home.

I do make sure to let F know that I can stop by and help with him again any time she wants. I say he was such a good boy, a total sweetheart, and no trouble at all. Little does she know why he’s such a good boy for me, it’s because I let him into my pussy whenever he sees fit to breed me. After all, until the sad, sad day that he’s neutered, I’m his bitch.

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