It was already a good day. Gwen was in the back of the Rustbucket, a good book in her hands, her slutty cousin riding her cock like his life depended on how much cum he could milk out of her.
Their summer vacation had only started the day prior, but she'd happily already found an arrangement with Ben to keep them both happy.
All she had to do was keep his cute, hungry bubble butt stuffed and he was pleasant as could be. And go figure, draining her cock into him regularly took the edge off her own stress as well.
Their grandfather was stunned by how well the two were getting along, unaware of how they spent approximately 90% of their time when he wasn't watching them.
Today they'd be camping though, so they wouldn't have time for a good rutting later; hence why Gwen felt it necessary to give her cousin his daily load of cum now.
He bit down hard on his cousin's underwear, which Gwen had stuffed into his mouth to act as a gag, as Gwen bounced him on her cock, holding his hips as she thrust up.
She grunted with the rough thrusts, feeling every twitch of his tight hole as it milked her, bringing her closer to the edge. Ben dropped his hips to match the speed of Gwen's thrusts as best he could, shuddering at the pulses of pleasure shooting through him as her cock stretched his hole.
Finally she slammed his ass down hard onto her cock, burying it deep inside.
Ben whimpered against the gag-panties, tiny cock spurting cum over his stomach as he felt rope after rope of hot, thick cum filling his ass. He relaxed against his cousin, breathing heavily through his nose to try and recover.
No sooner had he done so could Gwen feel his hips wiggling, trying to her Gwen hard again while she was still inside him, knowing she wouldn't be able to resist even if it was a bad idea if he could get her going.
"Horny slut." Gwen groaned, biting her lip as she tried to resist and just pull him off of her cock.
She managed to get him off of her before she lost control, but not before his teasing had gotten her rock hard.
It would be an uncomfortable night she realized, one she'd have to punish him for tomorrow when they got back on the road. For now though, Gwen resolved to somehow make it through an extremely boring night.
She was instead treated to perhaps the most eventful night of her entire life.
For only a few hours after they'd stopped for camp, what they thought must have been a meteorite crashed into the woods not far from them.
Excited to see it, Gwen and Ben rushed out to see it. At least that was what they'd told their grandfather.
In truth, Ben's teasing finally had Gwen at her limit, and she was basically dragging the boy through the forest to find somewhere far enough away for them to fuck, too hot and bothered to allow Ben's ass to go unstuffed for another minute longer, and the meteorite had provided the only excuse that Max would have accepted.
But quite by accident, the two actually did stumble across the meteorite; quite literally stumbling, with Gwen tripping into the crater before either saw it was even there. By the time Ben got down to the bottom after her, his cousin had a new accessory on her wrist.
"What's that?" He questioned, looking at the strange black and green watch.
"No idea," Gwen said, sounding just as perplexed as her cousin, "It just.. Grabbed onto me."
"What's it do?" Ben questioned, grabbing at it curiously, ignoring Gwen's shout of, "Ben wait-!"
A flash of green, and suddenly Gwen was no longer human. Ben stared, wide eyed as his cousin grew several feet in height, her skin turning a deep red before cracking like stone, yellow-orange first erupting from between them. Within seconds she'd become a being made of fire.
At least that's what it looked like anyway. After the initial few minutes of panic subsided, Gwen swiftly realized she wasn't made of fire, at least not quite so literally. Whatever she was, it was organic, at least from what Gwen could distinguish from inside the body of one.
She saw little reason why an inorganic being would have a cock at least, but then maybe this thing hadn't been designed to transform a futanari. In any event, shortly after calming down, Gwen started putting together what this body of fire could and couldn't do.
Throw balls of fire? Yes. Control existing fire, no. Absorb existing flames, yes. Control the fire she generated, yes. Regulate body temperature, yes.
And it was this last yes that got her mind going. It took some testing, but Gwen could definitely get the temperature of her body low enough to make human contact without burning whoever she touched.
And after confirming this, and confirming she was still hard as a concrete slab from a combination of Ben's previous teasing and the adrenaline from the brief panic, Gwen decided to really put this new body to the test, not sure how long it would last, assuming she hadn't just been transformed forever (a panic attack she'd filed away for later just in case).
Ben gulped when he realized what his cousin was suggesting, not at all sure about sex with a being he'd just watch roast a tree by touching it.
Gwen assured him it was fine, giving his ass a rough smack. It stung of course, and more so than a normal slap, but not enough to make the pain greater than the pleasure, which was enough for Ben to give it a chance so long as Gwen promised to stop if it was too much for him.
Gwen agreed, knowing full well she wouldn't be capable of stopping once she started even if she wanted to. Gwen could barely control herself long enough for Ben to fully undress, nearly losing control and simply burning the clothes off; only stopping when she realized she wasn't sure she could do so without also burning Ben.
But Ben had only just removed the final article of his clothing when he was pulled off the ground by his horny, flaming cousin. He gulped nervously at the feeling of her red hot tip poking against his puckered hole.
Not only could he feel that she was thicker now than she was normally, but he could also feel the heat of it. He shuddered, growing stiff as well as he felt her push inside, that intense heat filling him completely as she pushed inside.
"F-fuck Ben~" She groaned, realizing how tight he felt now, how good his tight, cooling body felt around her throbbing, molten cock.
Her gentle moans turned rough in under a minute, going from gently working him up and down her heated cock to holding his hips as she hammered up into him. The heat ended up providing more pleasure than pain however, spreading warmth through his body and relaxing his muscles.
It allowed him to focus more on the blissful pleasure of it than the pain, and he found himself cumming the instant her red hot tip hit against his button. Gwen shuddered when she hit his prostate, feeling his walls clench around her cock so tight he felt like a pocket pussy.
Her grip on his body tightened as well, holding him in place like a sex doll as her hips went from rutting to ruining; abusing Ben's prostate with her heated cock, bringing a burning hot hand down hard on his ass every few moments or so to keep those adorable squeaks of his coming out to.
"Take.. it.. All~!" Gwen grunted as she reached her peak, each word punctuated with an especially rough thrust of her hips.
She ground her cock inside of her cumdump of a cousin until the heat reached its max. She sighed as she spurted hot, molten cum over Ben's button.
Max heard Ben's pleasured scream all the way back at camp, though assumed it was just a wolf breeding his bitch somewhere distant out in the woods, and made a note to warn Ben and Gwen then they returned to camp.