You pick the nervous man, Lukas, as your first test. Clicking generate sentence, the screen shifts to a text box and keyboard.
'A young man awaits the woman he met on a dating site.'
This prompt gave you plenty to play with, you could change "young" or "man" to change Lukas, "woman" to change whoever he's meeting, or perhaps the phrase "dating site" to something more interesting. Would changing "awaits" teleport her here to be doing whatever you replaced it with? You get to replace two words, so you could do a combination of ideas.
You could add a word instead, dropping an adjective in front of any of the subjects would change them to fit.
In the end you decide to change two words in the sentence, but in a way that wouldn't be immediately apparent to you. At least until Lukas' date arrives.
'A young man awaits the catboy he bought on a dating site.'
The app returned to the map screen, the button to bring up another sentence replaced by a minute long cooldown timer.
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Hannah got off the bus in the downtown area of the city. She was meeting a guy for coffee only a block away from the bus station, but a small car accident on the bus route meant she was arriving later than expected. She brushed a long strand of hair out of her face as she glances at her phone to double check the name of the cafe and make sure Lukas read the messages she sent about still being en route.
He stumbled a moment as an odd sense of vertigo swept over him. His ears pinned back and tail flicked in annoyance as he shook off the dizzy feeling.
Wait, tail? His?
Quickly surveying his body, Hannah finds that he looks like he could be the younger brother of his original body, if he had been part cat. Wavy hair in a short, androgynous style is parted by a pair of cat ears atop his head. His outfit had shifted to fit him better, although changed little from his previous sweater and jeans other than now lacking a bra and jewelry. A fluffy tail sways behind him, freed by an opening just under his waistband.
Hannah was scared by suddenly being in a new body. But being somewhat far from home and so close to the cafe already, he figured his best bet was to still meet with his owner and figure things out from there.
.......owner?
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Back in the cafe, your timer finally finished allowing you to alter a new sentence. On the map, a dot had paused on the sidewalk for a while before beginning to move quickly again. You tap it, bringing up a second sentence.
'The catboy is nervous to meet his new owner.'
Looks like his name is Hannah. Not very cat-like, or boy-like, but you think Lukas can come up with something better.
'The unnamed catboy is nervous to meet his new owner.'
You submit your addition just as you notice the catboy in question opening the door. He pauses for a moment on the threshold, scanning the room before noticing Lukas and the shiny cat collar that had suddenly appeared in front of him.
He sits down and the two start talking quietly for a bit before reluctantly going to order at the counter. It's obvious that the catboy is in distress over losing his old body and name, and Lukas seems uncomfortable too.