Oh man it all started when I was a teenager....about 15 I think
I Had a very shitty childhood and as I was coming of age and hitting puberty I was locked in my room in the back of the house a lot with along with our 3 dogs 2 German Shepard and a Rottweiler we named Rosco because my parents idea of dog ownership was just owning them....not really taking care of them, so I was the only one who took care of them....whenever I would sustain a beating and get thrown in my room or sometimes when I would just be feeling down our large Rottweiler Rosco would come along and sit with me to comfort me, he would lick my knee or hand just to let me know he was there and he was always laying his head down on my knee for behind the ear scratches, he was the closest thing I knew to compassion,
One day everyone was gone and I had just taken a shower and hopped out and he playfully ran up to me and buried his snout in my crotch and started licking, at first I kinda jerked back, but a rush of hormones and me being a horny teenage boy, I was enticed to let him keep going, so I did...he licked all over the tip of my penis and started licking around and under my balls and finally reached the rear where he started licking my butt cheeks so I bent over a little more so he could get better access to my ass, and he started licking intensively once my rectum had relaxed from his constant licking he almost started penetrating me with his tongue trying to get deeper I guess...it felt massively good
So out of curiosity and hormones at the time, I wondered what would happen if I got down on all fours...as soon as I did he mounted me and grabbed me tightly around the hips with his front paws and started humping, at first he was just kinda poking all over the place but I moved my butt until he hit the mark and suddenly he went all in, as deep as he could go, in and out repeatedly which was both a surprise and a bit painful but the pain faded and soon turned to ecstasy, and as he was still humping I started to notice that he was getting stuck inside me (my first knot knowledge...lol) pressure was starting to build up...and not the good kind...more like the kind of pressure I couldn't escape from if I let him keep swelling inside me...so I pulled myself foreward and reached back and pushed his hips away until his knot popped out and after that it was bearable and wasn't painful anymore so I decided to let him cum inside me as long as he wanted
I noticed that I could feel the throbbing of him ejaculating inside me which I found absolutely captivating...I was rock hard by this point and between what was happening and the rush of hormones I was leaking cum out of my dick so I reached down to start jacking off just to increase the stimulus and started cumming ridiculously hard ....and jesus...I had never felt any ejaculation like this before...it was almost as if it was draining the soul out of my body, it was making my legs weak and I was making a huge mess on the floor underneath me because I wasn't prepared for this but it felt so good I just didn't give a shit so I came on the floor it felt way too good to even care (I later learned to keep paper towels handy for mess cleanup afterwords)
He was still grasped tightly to my hips and Cumming inside me and for some reason started licking the back of my neck, like he was trying to either calm me down or get me to stop moving, I'm not sure but it seemed so passionate and his warm tounge on the nape of my neck was actually pretty calming
So now I was just sitting here with him pumping away inside of me still grasped on tightly to my hips and a puddle of my own cum underneath which was mixing with his that was leaking out of my ass, so finally after about 30 minutes had passed once he started to go limp and he pulled out and a puddle of his cum gushed out behind me, I was a bit shocked because it was way more cum than I could even produce but that made it even hotter for me...I enjoyed the hell out of this and was just amazed by what had just happened...I got up to find a towel or something to clean up in a hurry before anyone could come while at the same time my legs where shivering and weak because of the orgasm I had just had so at the same time I could barely walk, lol....this was my first experience and after that we had MANY more sessions afterword, he would come up to me and I could just see in his eyes exactly what he wanted, if the family was around and I couldn't get into a full flung session with him I would find an unoccupied room and jerk him off so he could at least get some relief until we could, also it took me about 6 or 7 months until I worked up to the point where I could keep the knot in and have it pulled out without causing too much damage
He was the best Rottweiler...and mate and partner I ever had....I left my shitty parents house a couple of years later and he stayed behind because I didn't have a home to myself to keep him as I started off as a roommate with a friend of mine =(
I don't know what it was about him...how he would grasp me tightly or lick the back of my neck but he was an amazing partner and I miss him to this day, I've had many more encounters and knotting sessions with other dogs (More than I can count) but it's always him I'm thinking of....I haven't talked with my parents in 25+ years but I just assumed he is long gone by now but never forgotten
Anyways that's how it started and became the dark little secret I've practiced even up to this day....