I'll freely admit, this is an OLD story back when my writing was pretty shit.

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Jenny and Joy wandered through the tall grass of Kanto for some fresh air for a date the two were on. Jenny wasn't sure how it started but the two had begun to argue and in the process, Joy had fallen.
"Jenny give me a hand up." Joy snapped unaware of a creature moving through the grass towards her. Jenny, however, saw the creature unaware of what it was.
"J-Joy there-" Jenny tried to tell her but the nurse didn't let her finish.
"What? What is- AHH!" the nurse wailed as a large black and red blob began to envelop her officer Jenny stared in shock unable to even move. The officer tried to move but something spoke in her head.
"No. Just let this happen, I think you will enjoy the outcome." the voice whispered. The black mass slowly sliding up up the nurse, Joy struggled but was barely able to annoy the living blob. More and more of nurse Joy was absorbed by the mass.
"Jenny help me!" the nurse begged to her paralyzed girlfriend. Jenny stared in horror at the girl she loved being enveloped by the living ooze, soon covering Joy's head. The goo now completely covered the helpless nurse, the blob wriggled and smoothed out before changing from its shapeless form into a much more human shape. The police officer watched as the blob transformed into a human, not just any human but nurse Joy.
"So my dear what do you think of my new form? I like this form, and she was so tasty." the joy duplicate smiled. Jenny could finally move and speak, she struggled to speak or even think.
"What did you do to her? What happened? WHAT ARE YOU!" jenny shouted to the new Joy who just stared with a smile. The duplicate Joy moved closer to Jenny smiling cutely.
"I ate her for lack of a better word, and I don't know what I am or my name. So call me Joy alright?" the being continued to smile eerily. Jenny stammered but for some reason didn't feel angry or even upset. Instead, she found her self enthralled by the being as she noted a few differing traits of this Joy and the one it had absorbed such as purple hair rather than pink, the hair not in its normal rings and her eyes were very icy rather than their normal gentle blue. Jenny nervously gulped.
"I take it I'm next on the menu." Joy laughed at the comment.
"Hardly, actually if you don't mind maybe you could help me find my next meal? I'm sure you could find me a few cute girls to gobble up." Joy licked her lips as she spoke.
"Wait you want to eat more people! And for me to help you! Are you insane!" the police officer yelled in horror. Joy just chucked before speaking.
"Of course. I mean after eating pokemon then too eating your girlfriend the taste difference is staggering. She easily beat anything I've ever eaten and I know you humans would be far more delicious than any pokemon. So please find me, someone, to eat. Joy placed a gentle kiss on the officer's cheek "please."
Jenny stammered to try to argue but nodded.
"Okay." she set off to find someone for Joy to eat.

"What am I going to do? Who could I even give her? I couldn't give her one of the people in the town, maybe a traveller or a trainer. Gah, why am I even doing this?" Jenny mumbled to herself trying not to think about what she was about to do.
"Hey you give me your Pokemon or nobody gets hurt!" a woman's voice bellowed at her. "Wait I mean and somebody gets hurt wait, no I mean screw it just give me your pokemon"! Jenny spun round to find a flustered team rocket grunt trying to be intimidating, rocket grunt, honestly it was more funny than threatening. Wait maybe I can use her, after all, no one is going cry for a rocket grunt going missing Jenny thought to herself.
"Hey if you want my Pokemon they're yours just don't hurt me and come get them." Jenny played the damsel grabbing a Pokeball she had just to get the grunt's attention.
The grunt shook her head in shock "That worked? I mean good, you stay right there and I'll come get it!" the goon was clearly excited about the mugging seemingly going well and rushed over. She reached for the ball only for Jenny to locked the hands of the crook in handcuffs.
"Thanks, you just solved a problem I was having."

"Joy? Joy I brought you, someone." Jenny called for the unknown being, who appeared from behind her.
"Oh, she looks cute and she's all for me. What a good girl you were to bring her to me. She looks delicious." Jenny turned to face the hungry creature dropping the grunt in the process. Joy reached out and teasingly caressed Jenny's face. "I'll be sure to reward you for this but first dinner." The being grabbed the grunt's head pulling it into her impossibly wide mouth. Jenny watched as the creature began its second meal. Slowly pulling the unconscious woman in like she was nothing but a large meaty noodle. As Jenny watched again she found herself unable to take her eyes off the display, watching intently as the thug slid deeper down the waiting gullet, watching as the goon struggled to be free upon waking though it was far too late. The last of the grunt disappeared down the false Joy's throat, Jenny felt suddenly sad that it was over she had wanted to enjoy the sight longer.
"So that's what eating with a mouth feels like. I'm going to enjoy that feeling. Now for you sweetie." Joy turned to the distracted Jenny who jumped at the call. "I'll take very good care of you but I hope you'll take care of me in turn." Jenny looked down at the bulging gut then back up to Joy's face.
Alright. But what are you going to do for food and people will notice the real Joy missing. " Jenny tried to reason only for Joy to chuckle again.
"I'll run the Pokecenter and maintain the illusion that I am joy and I doubt anyone will notice a few trainers or tourists disappearing." the creature had won, Jenny was it's willing servant and the town and all who came to it its food