Sam winced as the first twinges were felt in his muscles and groin. He felt a dull ache settle into his bones as he felt his chest begin to push out and barrel with new muscle. He was confused at first as it felt like his sternum was growing a keel, but Sam's attention was drawn to the hard and throbbing cock jutting out from his groin. His eyes went wide seeing his manhood grow even larger as is became a tapered point with barbs, a feline tool more at home on a rampant lion than a man.
Sam groaned as sensations washed over him. New thoughts and instincts began to run through his head... urges to claim a mate for life. Sam shook his head as images of Fiona pinned beneath him as he rutted rose unbidden to his mind. Thoughts of her round, gravid, and pregnant with... eggs? Sam shook his head at the bizzare and arousing thought.
As he reached for his dick to get some relief from the raging arousal gripping his leonine tool, he saw his hands and felt them cramp as the skin yellowed and dried. With a series of wet cracks he took a ragged breath watching talons grow and push his finger nails off as his hands were molded into a giant pair of eagle talons, scales running up his arm. Aches spreading through his whole body as it twisted and warped, Sam was forced to his hands and knees when his hips made a wet cracking pop sound. His new avian talons clutched at the floor digging small furrows into the hardwood. His legs now following as his feet lengthened, toes swelling into massive leonine paws.
Again Sam wrestled with another flood of instincts, demanding he find his love Fiona and mount her. Possessive thoughts of owning and breeding her run through his new gryphon mind as he thought of Fiona as his bonded love, of her egg heavy form praising him as he addded another woman to his pride. He gasped and the vision of Fiona shifted to her heaving and clenching as she laid her first egg.
New sensations began as a second pair of shoulder blades formed and a tail began to snake out of his spine, how horizontal to the floor like a beast. Two arm like growths took advantage of the new shoulder blades and quickly sprouted the long primaries and flight feathers of a wing.
With each pause in the transformation he had been assaulted with new thoughts, instincts, desires, and drives. Sam wondered which of these were his new bestial form's base nature and which were Fiona's own unspoken kinks and desires reaching him through the potion. His will faltered slightly at the thought that this is what his mate desired, so why not indulge her as the matron of a horny gryphon's pride. She deserved to bear his eggs and help him find others who would fulfill her saphic desires as he kept the whole lot filled with eggs.
Finally overtaking his head, Sam's cries continued to deepen and also take on shrill notes as a syrinx formed and his face pushed out into a hard raptor's beak. His ears now perched on top of his head, swiveled to every sound and echo. His eyes focusing on objects with insane levels of detail and clarity, momentarily giving him pause as they zoomed in on something in the distance while a new nictating membrane allowed him to blink without needing to close his large raptoral eyes.
With a eagle's cry that dropped down into a lion's roar Sam's changes came to a slow stop. His wings half unfurled as he looked at his new lion sized 600lb body. The form of a mythical predator, a gryphon, staring back at him in the mirror.
As new and twisted thoughts rolled around in Sam's mind, his ears swiveled to the side. He heard Fiona's keys in the lock. She was home from work now.