Derrick whispered into the redhead's ear "Make me your identical twin!"
In response, the boy twisted around and threw his arms around Derrick's neck, pulling him into a forceful kiss with a lot of tongue. Derrick responded as best he could, then gasped as the faun broke away and stood. This put the faun's partially-erect goat cock just a little higher than Derrick's mouth. Rising up to his knees, Derrick took the oddly-shaped animal penis between his lips and started to lick and suck at the tip. Pre started to dribble almost immediately, and he swallowed the thin salty fluid.
Derrick heard the other fauns laughing and talking, but they were speaking Greek again and he did not understand any of it. All that mattered was the hard goat cock now being thrust into his mouth. More pre came, and he had his hands on the faun's furry buttocks, fingers sliding up and down the crack. When he found the animal anus under the faun's tail, he pressed at it with fingertips. massaging the curiously slick, soft opening.
The faun was grunting and bleating now, his hands grabbing at the hair on Derrick's temples. Derrick could feel the cock pulse, and then nearly choked as a hard spurt of thick semen shot into his throat. He coughed, but was able to keep it all in and swallowed the goat cum. Another jet came, but this time he found it easier to breathe and swallow. The faun's handhold shifted to his skull, solid and odd, pulling his head hard against the faun's crotch. Derrick could take the whole length in now, no longer gagging even though the tip was hitting the back of his throat and the huge goat's testicles were slapping against his chin. A third and final ejaculation forced goat cum down his throat, but Derrick easily swallowed it all. They remained together for a minute, both sweating and flushed, until the faun pulled out of Derrick's mouth and knelt to embrace him.
They kissed again, this time much more passionately. Derrick had to tilt his head down to meet mouths, but realized their height was not as different as it had been before. When they broke apart, he looked down at himself. The slight body hair he had started to show was gone, leaving his smooth-chested as the boy. However, below the waist he had developed a respectable copper-colored growth that was not fur yet, but getting there. And his cock was not only obviously larger, but developing a sheath.
The faun grinned and took his hand, standing and pulling him up so he could be led over to a still pond. They had quite an audience - all of the other fauns were staying close, watching them with grins and lewd looks. Even though they had just watched him suck off the satyr, Derrick felt no shake or embarrassment, only curiosity. The faun pulled him back down so they were both kneeling at the edge of the water. Derrick stared - his reflection was almost unrecognizable. It was still his face, though now he looked closer to 12 than 15. But his hair had a definite reddish cast and his eyes were the gold-flecked bright blue of the redhead beside him.
As he started at his reflection, the faun shifted back and then slipped over his back. he felt the hard prod of the faun's cock against his anus and was amazed that the boyish male could be erect again. Then he gasped as the faun thrust in, pressing into Derrick's surprisingly receptive opening - he had expected pressure and pain, but Derrick was loose and slick. They rocked back and forth as the faun drove deeper, grunting and gasping as Derrick's muscles contracted around the hard cock. Derrick caught sight of his reflection and realized it was changing. His attention flickered as the faun continued to pound against him, creating an almost stop-motion effect transformation.
His face got younger, and his coloring altered to be identical to the faun mounting him. He looked like an older brother now, maybe 12 to the faun's ten. Semen gushed into him, and he bleated in pleasure. Bleated? Yes, the sound was animal. Derrick did not care. Another jet, and the reflection was eleven now, his features no longer recognizable as him. They continued on, dropping sweat, grunting and bleating, the faun on top of him impossibly shooting another half-dozen jets of thick goat semen into Derrick's body until his insides felt bloated and semen was being forced up into his stomach. Finally, the faun simply collapsed over Derrick's back, penis still buried up his ass. Derrick had to blink away the sweat, but saw that he and the faun were now identical. No trace of Derrick remained in the face or body. He had become Anton.
Huh? Who was Anton? His twin brother. Derrick felt some confusion as he discovered new memories in his head. Memories of being born a faun, or a lifetime playing and having sex with his identical twin brother. Many, many years. Though the faun looked like a boy of ten, he was actually well over fifty. They did not age like humans. It would take another few hundred years before they even looked as old as Derrick had been. He knew many things now, fifty years of knowledge that made his original 15 year-old life almost negligible. But it was all knowledge of fauns and satyrs and sex and magic. What did he need calculous and history for? That knowledge was being pushed aside.
"Let it go." Anton whispered in his ear. "You are one of us now. You and I are two bodies with the same soul. Accept it all! There is nothing to go back to. If you returned to being human you would be a ten-year-old human version of what we look like now. Not the teenager your family would recognize and take back. You can't even speak English any more."
That last startled Derrick, who was still dazed from the sex and the transformation. He had to work it out carefully, but realized that Anton was speaking Greek. And Derrick understood him perfectly. He dredged up memories of school text books, or road signs and scraps of television programs and movies. None of the written or spoken English content made any sense to him, even though he could recall it clearly. It was all strange symbols and noises.
"Finish it." Anton pulled out of Derrick's anus with a slow movement that made Derrick shudder in pleasure. The former human was rock hard, the unfamiliar goat's cock and testicles throbbing with need. His twin turned to present his own rump and flicked his red-furred tail up in invitation. "Mount me and you will stay my twin forever!"