Forceful transformation

Devlin snuck into his roommates bedroom. He had heard him snoring and figured out it was time to put his plan in motion.
Quiet as an mouse he moved around in Martin´s bedroom and produced a small pouch from his pocket. Carefully Devlin began to sprinkle it all over Martin whilst reciting latin phrases.
It didn´t take long for the changes to start happening where Martin was changing form from his male physique to the more slender female. Devlin watched the changes with glee.
After a short while there was a sleeping woman in bed instead. Nice hourglass body, big butt and big boobs. And most importantly, her vagina was easily accessible.
Devlin had been wearing protective clothing but now he removed everything until he was totally naked.
 
He stroked his cock up and down to make sure it was firm and ready. Satisfied with the firmness he applied lube to his cock to make the first penetration much easier.
Without hesistation he mounted the sleeping woman from behind and began to pump his dick in and out with fervour.
 
It was the worst wakeup Martin ever had, as he felt something moving in and out of him, and someone heavy pinning him down. He tried to push the intruder away but he lacked the strength and was pressed down.
Devlin was focused on the task to keep pumping in and out and soon he was rewarded with the first female moan from Martin, who struggled lesser and lesser.
“You´re mine now, bitch”, Devlin growled as he released his load of semens into Martin.
The jets of semen triggered her orgasm as well and Devlin felt how her vaginal muscles spasmed against his cock. Her eyes rolled back up in her head and something clicked in her mind.
“Turn around”, Devlin ordered.
She did as she was told.
“Who are you?”, he asked.
She was quiet for some seconds, searching for the answer, before she remembered. “I`m yours, Master”.