Karla Ebbledeen sits on the couch, a young child on her lap, a blanket over both of them. The mid-40's fox lady has been running her babysitting business for a long time, and she's gotten more than just steady pay out of it.
The child, 6-year-old deer Sally Sue, has been rather quiet for some time, engrossed in the M-rated films her awesome babysitter is letting her watch. The girl is a hybrd, though the only non-deer feature she has is her wolfish tail. It rubs idly against Karla as the little girl stares absently forward.
It's time for Ms. Ebbledeen to make her move.
FWWIP RUSTLE
The babysitter pulls down her pants, letting her cock pop up and push against the little girl's bottom. She grips the child firmly.
"Miss Ebbwedeeen, what're you doing?" she asks.
"Oh, I'm just getting to my favorite part of babysitting," she says with a grin as she unbuckles the girl's overalls and slips them off of her, followed by her shirt. 
"Is it bath time?" the still-confused girl asks.
"Mmmm, you could say I'm going to give you a bath of sorts~" Karla replies.
Poor Sally is still clueless, but is starting to catch on that something is wrong as the babysitter removes her panties. The girl isn't even in bras yet. Karla leaves nothing but the little bow in her hair. The babysitter moves her to a position where her arms are pinned between her back and the babysitter's front, allowing her to hold the girl in place with just one hand.
"Can you-... You pwease let go off me?" the girl sputters out.
SLRRP SCHLK
Karla really smiles now as the little deer girl's wolf tail gets slurped into her shaft. All it takes is one quick tuck to get the tip of the tail into the tip of the shaft, and the entire tail soon disappears, making the cock appear thicker from how it stretches it out.
SCHLRRPLK
The experienced babysitter puts her hand loosely over the little girl's mouth to muffle her, just so she can't scream loud enough to alert anyone outside. She makes sure it's still plenty loud enough for her to drink in the sound. The panicking child does not disappoint.
Just as the end of the tail disappears into the babysitter's shaft, Karla's phone lights up and a cutesy ringtone plays. She recognizes the number as that of the girl's mother.
"Shame, I wanted to hear you scream a little longer~" Karla says in a sing-song voice as she reaches for the bag she'd brought with her in the seat next to them. She's gotten more than adequate at completing the next part quickly.
First she retrieves some duct tape; she forcibly holds closed Sally's mouth to apply it generously across her snout. Then she grabs a thick cloth gag and wraps it around the small girl's head overtop of the tape. That alone is enough to render her barely audible. She won't come through on her mother's end of the phone at all.
CLICK
"Hello, Ms. Sue," Karla says in a delighted tone.
"Hey, Karla; how's Sally?" the mother asks.
"I just put her to bed," the babysitter replies, "I know it's a bit earlier than the time you gave, but she said she was getting sleepy, and I figured she could use the rest."
"Oh, really? Wow! Sally never goes to bed without a fit," Sally's mother replies, audibly impressed.
Karla laughs a bit as she tucks the little girl's rear end into her shaft, her cock stretching out very wide to accommodate her inside of it, "Well, I have my ways. Wouldn't be such a popular babysitter otherwise."
"Yeah, sounds like you really lived up to the reviews, then! Maybe she'll learn something from this," the mother says.
The babysitter stuffs the little girl a few inches deeper; her legs are folded up with her torso as she's forced inside. She replies over the phone, "I'm sure she'll never have a problem with bedtime again."
"Y'know, I was concerned about the big up-front cost you had on your website; normally sitters ask for only half the pay beforehand, but I can see why you charge so much now," the mother says enthusiastically.
Karla stuffs Sally a good few inches deeper, enough that a few of her fingers graze her urethra from behind her back, just enough to get her right hand pulled inside, then her left. The girl, who now soaking her gag in tears, renews her struggles and fights furiously with her arms and her half-swallowed legs.
SCHLRKK SLRRRB
"Oouh-ahhh-" Karla lets out a shaky moan of pleasure as the girl fights.
"What was that about?" the mother asks in a curious but not suspicious tone. She sounds almost humored by the weird noise.
"I was drinking some ice water, and I just spilled some all over myself. Super cold," Karla responds in a tone that's lowered enough to sound irritated but not enough to sound at all threatening.
"Oh dear," says the mother, "Well, I'll let you go so you can clean that up."
Karla hesitates a moment, tempted to ask her to stay, to keep her talking for longer while she stuffs her only daughter down her cock to be churned up into cum, but she decides she'd rather focus on just getting the girl inside of her, "Alrighty, then. Have a lovely night."
"You, too, Karla."
CLICK
Karla looks down at the girl, who looks back up at her. There's a clear look of despair in her eyes as she recognizes what just happened, the impossibility of anyone coming to save her. She no longer struggles; even the half of her legs not inside the vixen's cock have stopped moving. There's just still, silent terror and a lot of tears.
The babysitter savors the sight of it like the finest of wines.
SCHLRRRFK
And immediately stuffs the girl much, much deeper, letting out a loud moan as she does.
"You little cock snacks always feel so good~" she says as she grabs her phone to snap a picture of the girl's shoulders and feet sticking out of her cock, "You'll look perfect in my album~"
SHLRRGPH SLOSH
With a final push deeper, the little girl is slurped down entirely, finding her way into Karla's balls and curling up inside them. From the outside, the whole ordeal must've looked like the girl had simply disappeared under the blanket.
Karla revels in the feeling of the giant mass slipping down her urethra into her nuts, her dickhole left with a satisfying gape from it all. She feels as though she's already going to orgasm.
She holds herself back from cumming prematurely and wraps the little girl's panties around her shaft.
PLAP PLAP PLAP
SWISH GLRRRG CHUUURN
Masturbating as vigorously as she dares with her victim's undergarments, Karla carefully edges herself while little Sally begins to lose form inside of her. As the child begins to melt into cum, she picks up her struggles again, only making the babysitter feel even better.
When she starts to get really close, Karla gets up and walks to the girl's bedroom, her balls swaying heavily between her legs and only sloshing around their passenger more, speeding up her digestion. She continues edging as she walks.
PLAP SLAP FAP
GLRRRFGH SLORSH GWWWRRRR
Finally, the babysitter aims her massive member at the wall just above the girl's bed, the broad back of her panties covering the tip of her shaft, and she releases. 
RIIIP SPLAFBTBLRF BLRSPLBLFTP
An enormous spray of cum rips through Sally's panties and gushes out of Karla's cock, sprinkled with hundreds of little bones. The spray paints the wall and runs down onto the bed as a half dozen bones embed themselves in the drywall. A cum-stained gag lands on the bed.
SLBLRBLSFPT THUD THNK CRRTHUG SPFLBLRPT
A femur, some ribs, her pelvis, and of course her skull all poke out of the wall, each glazed with cum that used to be the rest of the small girl. Karla beats off furiously as she finishes, and with the last of the spray a very cum-drenched pink bow splats out and lands in the girl's left eye socket.
The babysitter huffs from exhaustion as she looks up at her impromptu mural. She takes a picture of her handiwork and jokingly saves a caption with it.
Title: What's Left of Sally Sue
Medium: Former child on drywall.
Finally, Karla collects the gag and puts it and the cum-stained strings of fabric that used to be Sally's panties into plastic bags to take home. The former will be washed and reused on another unsuspecting child; the latter will be added to the babysitter's growing collection.
All that's left for Karla to do now is hop on her client's laptop to leave a positive review on her website, which conveniently can't be edited, set her voicemail to record any calls she receives from the mother's number, and leave with the payment already received.
Another satisfied customer.