Jared stared intensely at his older brother, grinning with a nasty look of anticipation. Jeff, scared beyond belief at what his Jared could possibly do to him, decided to make a run for it.
"Stop, bro", Jared said. His boyish voice carried across the room and hit Jeff like a ton of bricks. Jeff realized he already had used the Chronivac to give some sort of commanding power. He was entirely unable to move his feet. "Stand right there. I've realized my current body does not suit a being as powerful as myself. So as my first test, you're going to become an excellent 'steed' for me."
"Please Jared, I thought the program said you can't do anything evil!", said Jeff desperately.
"I know. You'll still be alive, just as a 'part' of me. Now take off your clothes big bro." Jeff quickly stripped against his will. "Wow, nice. A perfect studly body. We're definitely going to have to improve some of those areas though", Jared said with a wicked smile.
Jared dug into his brain, still getting used to how his Chronivac-enhanced mind worked. By focusing on Jeff he was able to see options to modify specific parts. Perfect! "Watch out bro, you may feel some pressure". Jeff cried out in pain as his hands and feet began to fold in on themselves, becoming large cloven hooves. Sleek brown hair grew all over his body and a horse tail emerged from his back. Jeff could feel his bones rearranging and his back snapping, forcing him to adapt a permanent four-legged stance. Curiously, his head had been spared of any changes. After a few minutes, Jeff was now a full-sized stallion with a boy's head attached.
"What the fuck, Jared! That hurt! I can't live my days out as some horse freak!" said Jeff, still unable to move due to Jared's binding spell.
Jared just smiled again. "Oh bro, you were just doing the hard part for me. Now be a good boy and come to master." Jeff felt himself moving slowly forward against his will. Instead of getting out of the way, Jared only turned around, stripped naked, and leaned forward a bit.
Jeff was now horrified. "What are you...what...what the hell are you?" He could only scream in shock when he realized what we happening. As his head made contact with Jared asshole he could feel it getting wider. The younger brother yelled in pleasure as he used his reality-altering powers to take Jeff's entire head. Once totally inside, Jared suddenly gained nervous sensation of his previous brother's horse body, now sealed with his. The feeling was too much as he ejaculated hard from his own human dick and Jeff's massive stallion cock, which he now controlled. Now useless, Jared's former human pelvis and legs shriveled away, leaving only the upper torso and head of a 10 year old boy attached to a fully-grown male stallion.
Oh yeah, Jeff was still here. Now part of Jared's tauric body, he spoke to Jeff through his mind.
"That was disgusting bro. Please, you can't be this evil. Let me out and I promise I won't be annoying anymore".
Jared considered...