Mark lived with his parents and his older sister Rebecca. He.. (OnlyFans)

Mark lived with his parents and his older sister Rebecca. He was a quiet person and loved his girlfriend Sarah with all his heart. The two bonded over the simplest things and shared a love for reading and watching transformation porn with each other. One day Mark saw online, a company developed a way to transform a human into a sophisticated ever-changing sex toy. Mark immediately thought about surprising Sarah with himself as a dildo and the thought alone excited him deeply. He wanted nothing more than to be wrapped between Sarah's velvety folds, filling her to the rim. So Mark set off a week later, heading to his appointment and eagerly ready to be sent out to be used!
Upon arriving at the massive building, Mark was overwhelmed by the amount of paperwork. Filling out a large packet took some time and some of the information needed He didn't have on hand. He was too eager to have this happen and if he was going to be delivered to his girlfriend by their anniversary he needed to finish this now. He quickly scribbled down his address and info then turned the paperwork in. A woman called his name and led him to a massive machine. He laid back in the machine and a dull hum was heard as the machine turned on. Light flooded his vision and he shut his eyes in response, as the humming got gradually louder. Suddenly a flash hit and he was gone. Only a white light filled his vision, no humming but he could hear papers and tape. Suddenly he was lifted up, he felt something grab him. It was warm but felt alien to him. Then it dropped him, he fell and tried to scream but nothing came out, he hit soft plastic and the light faded away around him. 

Eventually, Mark's vision returned to him. He saw darkness with a bit of light beaming in through the corners of his temporary prison. He now knew he was in a cardboard box with packaging material around him. He could feel the truck driving and stopping as the delivery man dropped packages off. Mark had done it. He was about to surprise his girlfriend with the perfect gift. They could share passionate moments together in bliss and then she could turn him back and they can experience each other like never before. The thought aroused and excited Mark in a new way he never experienced before.
After some time, the truck stopped and Mark felt his box lift up. His heartbeat was so loud he could feel it through his entire new form. The delivery man knocked, then some muffled talking above him before he was carried inside.

The box hit hard on the counter before Mark saw the tip of a blade pierce the box above him. His heartbeat intensified with excitement. Light flooded inside his box blinding Mark temporarily. His vision returned to see a vision of true beauty before him, a massive hand holding his instructions and a remote. Mark was hit with a bit of depression at not seeing his girlfriend's beautiful face but a hand. He looked on as the papers disappeared and a head began to fill his vision. However, Mark's heart sank when he saw his sister Rebecca smiling down at him instead of his girlfriend's face.
How could this of happened? Was this a joke? He tried to cry out but nothing formed. Above him, Rebecca read his instructions aloud.

"Living transforming personal sex toy. Can change size, and shape. New vibrating action. Hmmm." Rebecca said.

"Looks like the red button changes the size.." Rebecca read aloud pointing the remote at Mark. Mark's body tingled before growing in length within the box. He felt his body stretch in a pleasurable way before his head touched the box above him.

"Cool! Then the blue changes the shape?" Rebecca read aloud again, pointing the remote at Mark. 
His body tingled again, turning him on a bit before thickening and becoming more realistic looking. 

"Oh wow! This is so cool! Let's see... the black button is vibrate but what does the storage button do?" Rebecca questioned as she yet again pointed the remote back at Mark.
This time Mark's body tingled harder than ever before, he felt his body transform and shrink. His body turned inward on itself and it nearly made him climax if that was possible. His massive sister gasped above him.

"Whoa! This thing turned itself into a clit piercing?! I guess that's one way to store it hahaha!" Rebecca chuckled loudly above Mark before grabbing his tiny form. She lifted him up to her eyes as she smiled at his form.

"Oh, I've gotta try this thing out for sure..." Rebecca said while grinning ear to ear.

Mark cried out in silence as his older sister, now owner threw away his packaging and his only hope to be found before bringing him to her room. Rebecca set him on her dresser and morphed him back to his original dildo form. Mark was near climaxing again and hated the fact that it was his sister of all people making him feel so good. He watched in silent protest as his older sister undressed before him. Sliding her legging down her legs before kicking them off. She turned away and bent as she slid her panties down, revealing her curves and cheeks toward Mark. Mark was both aroused and disgusted as his older sister continued to undress, turning around, Mark locked on the massive tits swaying from Rebecca's chest as she walked closer and reached for him. 

Mark screamed and begged to be noticed as Rebecca positioned herself on her bed. Lowering Mark, she turned his face towards her vagina and slowly pressed Mark's face against her. Mark rubbed over his older sister's pussy lips, and clit as she slowly pleasured herself using him. Rebecca leaned back more and clicked the black button on Mark's remote. Mark instantly began to vibrate rapidly as he slid around her clit. Rebecca moaned above Mark before Mark felt the orgasmic tingling once again. Mark morphed once again to a thicker realistic-looking dildo, crying out in orgasmic pleasure just before his head slid between Rebecca's lips. Mark screamed as he entered his sister. Rebecca started slow, pushing Mark's dildo form deep into her now sopping wet pussy. Filling herself unaware of what she was putting her brother through.
Mark began to slide out, stopping before his head left his sister and once again filled her fully. Again, Mark slid in and out, slowly increasing the speed as Rebecca moaned above him. Mark felt guilty as his sister moaned above him. She felt so good, filling her each time sent waves of pure bliss over him. He was on the verge of climaxing any minute now as his sister greedily pumped his form deeper and deeper into herself. Suddenly he felt Rebecca's vaginal walls getting tighter, she pushed him harder than before deep into herself as her walls clenched Mark's dildo form. Mark came harder than he ever had before just as Rebecca climaxed herself. Rebecca fell back and relaxed as Mark slid slowly out of his sister's lips, plopping in a small pool of her juices on her bed. Mark felt so disgusted and confused. He lived out his deepest fantasy but had to do so with his older sister, not his girlfriend like he imagined. It was even better than he ever thought but he couldn't shake the disgusting thoughts of his sister.

The cool air of his sister's room began to dry the juices on him as his sister heavily panted above him. He tasted all of her juices from every angle, they tasted...good? Like something he never experienced before but it tasted good. Mark sat in the pussy juices thinking about his experience as Rebecca sat up. 

"Oh, baby! This is so damn good... I wonder..." Rebecca thought aloud.

She grabbed Mark's dildo form before changing him into a sleek design. Mark tingled again, this time his pleasure seemed to almost hurt. Rebecca grabbed some lube and began to drench Mark. The lube hit Mark and a faint taste of strawberries filled his senses. Rebecca rubbed his sleek form and sat up on her knees....

Stay tuned for part 2 later today. Only fans wouldn't let me post it all at once.