This is also part of my "Biorubber Kurose" series. I thought I'd also share a stream-of-consciousness look at the plot notes I had in mind for the story.
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Setting:
Let's call the slightly overweight professor who was turned into biorubber "Kurose."
Kurose has always had a hedonistic personality. Since becoming a biorubber, he has no sense of pain and almost everything he does feels pleasurable, which has caused his hedonism to escalate.
Because of this, he doesn't think very seriously about turning others into biorubbers or pets; he treats it almost like a game.
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Story Outline
Introduction (Ki):
The protagonist is another one of Kurose's friends. He's a rubber fetish enthusiast who especially enjoys "puppy play"—dressing up in things like puppy masks to act like a dog. He gets in touch with Kurose for the first time in a while (unaware that Kurose has become a biorubber).
The story leading up to Kurose's arrival is kept short. The protagonist finishes a shower and starts changing into his costume near the bathroom, reminiscing about his plans to meet Kurose tonight. → As he checks himself in the mirror, Kurose emerges, oozing out of the shower head behind him.
Development (Shō):
As Kurose takes shape, the protagonist, though bewildered, finds his eyes drawn to the living rubber body, moving slickly and sensuously. He asks Kurose what on earth is going on.
While listening to the story of Kurose's biorubber transformation accident, the protagonist has an improper fantasy: "(I wish that accident had happened to me)" "(Why wasn't it me?)." However, his rational mind holds him back for a moment.
The plot develops to where he gets Kurose's permission to touch the biorubber body. As his touches become more intense and he gets more and more into it, could this lead to him confessing his own desire to become a biorubber?
Turn (Ten):
Hearing the protagonist's confession, Kurose nonchalantly tries to stop him once (just as a formality), saying something like, "Are you serious? You know this means you won't be human anymore, right?" The protagonist hesitates for a moment, but his attraction to the rubber body is undeniable, and he makes his decision.
Kurose doesn't actually know how to turn a human into a biorubber, but he says, "Perfect timing. There's something I wanted to try," and decides to experiment...
He extends a phallic appendage, rubs it, and ejaculates. The idea is that his rubber semen is meant to soak into and remake the material... (This part should be conveyed subtly without being too expository, or perhaps with no explanation at all).
Transformation Scene:
The protagonist's costume melts and mixes with Kurose's rubber semen, which then begins to invade his body.
At first, it's painful, but the sensation is quickly overwritten by intense pleasure.
Include a description of the costume's studs, fasteners, and wristbands fusing with his flesh.
A large amount of Kurose's rubber fluid is absorbed into the protagonist's body, becoming new cells and muscle tissue, improving his physique. → The idea is that the rubber fluid increases his body mass.
The transformation is complete, creating a muscular, beefy biorubber dog-anthro!
Conclusion (Ketsu):
The protagonist rejoices in his new form and overflowing power.
When Kurose playfully asks him to offer a paw ("Ote"), the protagonist tries to scamper over on all fours, which causes him to transform further into the shape of a dog itself (imagine a large, muscular Doberman). While the protagonist can't shapeshift as freely as Kurose, he has gained the ability to switch between his dog-anthro and full dog forms.
The protagonist asks Kurose to be his owner and presents him with a collar. Kurose, still in a playful mood, puts the collar on him. It fuses with the protagonist's body, and the two become master and servant.
Excited, the protagonist pins Kurose down in an erotic way. They start fooling around. The end.
That's the general image I had in my head (though some parts might be slightly different from the final illustration).
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August, Week 2: 1Hour Drawings
https://www.patreon.com/posts/136055509/
My sincerest apologies for the extreme delay.
The winner of the one-hour drawing poll for the second week of August was... #2,
the Rubber Puppy TF!
Options #2, #3, and #4 were neck and neck for most of the poll,
but #2 pulled way ahead at the very end.
Thank you all for voting!