The inhuman power I was feeling was so overwhelming, I nearly lost my sanity within seconds of completing the transformation! I was not aware of it, but I was now snarling and drooling and my erection grew to a size that surpassed any living human's. Meanwhile, Runt was standing a few feet back, staying cautious but watching with eager attention. "Well, well, well! Somebody's forgotten their manners around their guest. Guess I'll have to -- YOW!" His remark was cut short as he was lifted several feet off the ground by a pair of massive clawed hands around his shoulders -- my hands, natch. The imp just grinned nervously and muttered, "Don't care for sarcasm, eh?"
Before I even knew what I was doing, I shoved Runt's tight asshole squarely on my cock, facing torwards me so I could see the look on his face when I filled his colon all the way up to the rib cage. Shock and confusion were written all over him. Just the sight of the imp's horrified face was enough to give me a primal sense of lust, and an unquenchable desire to dominate him further. I gripped him by the waist with both hands and pumped him up and down on my member, leaving him utterly helpless to resist or even move. At this point, I fully expected him to start crying for mercy... but it didn't come. In fact, his shocked look was now a pervy smile.
The imp could barely speak clearly, since I was manhandling him like a bag of potatoes, but I managed to hear him shouting between grunts. "Agh~ You caught me off guard, mate! Uff! But I am an imp you see, and-- mmf-- I can stretch my own arsehole like rubber, just as I can others!" Just as he said, I was now feeling a super-stretchy, rubbery texture on my penis instead of soft and wet. Runt had begun masturbating himself, apparently feeling no discomfort in the slightest from my domination. Something told me I needed to go further.
I yanked the poor imp off my erection with a sickening "schlupp", and turned my gaze toward his face. He seemed to know what I wanted instantly. I wasted no time yanking his jaws open and forcing my malehood down his throat with no regard for his personal comfort. His gargles of protest were blatantly ignored, I was having too much fun embracing my carnal side! But just as expected, Runt simply stretched his throat out to fit me, furiously masturbating like it was any other dick suck. Honestly, I began to suspect he was leading me on at this point. Although it wouldn't hurt to get off inside him just to finish the job.
We were both lost in demonic pleaure now, unable to form any thought that wasn't animalistic lust. I was clutching Runt by the head and roughly humping him in the mouth like he was a sex doll, and he was jacking off with one hand and fingering his ass with the other. He let out a muffled scream of pleasure, just before busting his nut all over my legs, feet, and the nice carpet. The load was huge for an imp his size, but it was still nothing compared to what I could give him. Holding my breath, I let out a deep snarl and prepared for the best orgasm I had ever felt up to this point. The floodgates opened and I filled Runt's stomach with a ludicrous amount of cum, enough that his small body couldn't hold it and the pressure ejected him from my erection. For several more seconds, I continued to climax, drenching Runt from head to toe, plus the carpet and walls and most of my furniture. Just before the orgasm became too much for my mind to handle, my balls finally emptied out and I got some well-deserved relief.
"PHWOOAR!" In my haze, I could make out Runt licking his lips and rubbing the cum all over his body. "I haven't been buggered like that since back in Hell! You really are a pure demon, in body and in mind!" By some miracle, Runt was still horny despite blowing his load only a minute ago. And I was getting randy again too! "By the way, mate, forgot to mention. Demons last for ages in the sack compared to humans... I'm talkin' multiple days of pure animal fuckin'. It's up to you what to do with that information."