“Now, Brian, to seal the deal, and make you my thrall.” The doppelgänger dismounted Brian’s half-hard cock, and returned the table to which he was strapped to its upright position.
Brian felt dizzy, and then a sense of lightness, as his human form lost its size, becoming elven once more. Although he missed his previous form’s sturdiness, he was happy to be in his original body once more. Looking up, he saw that he doppelgänger had changed as well, to its well-muscled natural gray form. It approached, and caressed his cheek with a cold hand. “Soon, little elf, you will be mine.”
Brian tried to shrink back, but he was still tied to the table, and unable to escape. He looked on in horror, as the doppelgänger grew a huge penis, longer and thicker than anything Brian had seen before (even on Mike’s well-endowed centaur.)
“No way you’re sticking that thing up me!” he insisted, panicked.
The doppelgänger only smiled, and reached around, grabbing Brian’s buttocks in his powerful gray hands.
“No!” Brian cried out, transfixed by the immense cock that stood fully erect from the doppelgänger’s heavily muscled form.
Smiling, the creature bent his knees and positioned his huge cockhead underneath Brian’s twitching hole. Brian thrashed about, trying to break free, trying to close his legs, trying to prevent his imminent impaling. All was for naught; Brian’s lithe elven form had little chance against the doppelgänger’s powerful physique. Without comment or ceremony, the monster straightened its legs, and drove the monstrous tool deep into Brian, eliciting a shriek of terror. Further and further the doppelgänger went, burrowing itself deep into Brian’s body, giving the elf the fuck of his life.
“Ohhhhh…” moaned the elf, as the doppelgänger’s enormous boner reached as far as it could go. The doppelgänger smiled, and began bucking his hips, thrusting inside Brian, trying to go a little further, eliciting screams of pain and pleasure from his victim.
“That’s it,” encouraged the creature, “this should be the final treatment – the one that makes you mine.” Then the doppelgänger came, and emptied a torrent of jism into Brian’s aching ass.
“NOOOOOoooooo…” Brian began, his scream trailing off as the doppelgänger’s seed did its insidious work. His skin became pale, and ashen, and he felt his body become stronger, and more powerful. The doppelgänger resumed its motion, fucking Brian’s ass with renewed vigor, his breathing heavy and excited. Brian’s skin changed further, and turned to gray, as his body finished changing, becoming a smaller version of the other doppelgänger’s. He was not quite as big as his master, but Brian was completely loyal and obedient. He relished the ass-pumping that he was receiving, knowing that it was making his master happy. He loved having his master ram that monster tool up his ass, because he knew that was what his master loved. More than anything, Brian loved his new master.