Ok I may be becoming minorly obsessed with this new concept so thank you @thunderandfrost for the ask!!
I may have to write this for my next mid-length fic...
Sylkior where Loki and Sylvie and twins and teenagers, and are sent to see their big brother Thor over their summer break because Frigga caught them making out and she's way too afraid to face the truth of their relationship, and just wanted to send them away, out of sight.
And Thor is more than happy to see his little siblings, especially since he moved all the way out to this cozy little double-wide in the middle of the woods in West Virginia. He just hopes he can keep his feelings under control.
And of course, he can't. Loki's gotten on testosterone, and the changes in his body just make Thor fucking insatiable. He masturbates to him every night, his body hair, that adorable little happy trail, what it might be leading to, his chest hair, his voice that's slowly lowering. Jerking off thinking of titfucking his little brother, then eating him out.
And of course Sylvie. He can't even think of her without immediately thinking of the time he caught her and Loki giving each handjobs for the first time, discovering each other's bodies as their bodies were developing. She seems to only wear the sluttiest outfits now, wearing just panties around the trailer, saying "We're all siblings, it shouldn't be weird if I'm topless." And of course Loki sat side by side with her, intertwining their legs while he also wears nothing but his boxers. Thor could almost make out the outline of her pussy lips from her panties.
And Thor can't help but notice those whores are doing it on purpose. They keep making out in the living room and loudly fucking in the guest bedroom he put them in, and Loki almost never wears a shirt anymore. Just showing off his hairy tits and stomach. Loki being sure to bounce and jump whenever possible, as well as getting wayyyy too close for comfort with his big brother, rubbing his tits up against his rough flannel shirt and barely suppressing a moan as his puffy nipples rub up against the rough fabric. Thor pulls him closer and Sylvie enters the living room, this time completely naked. She completely comes and sits on Thor's lap, right on his raging hard on, wiggling her ass and wet pussy on his jeans.
"What movie are we watching?" She asks, leaning in with Loki so close their breasts are touching.
Thor slowly moves as Loki explains the plot of the movie to Sylvie, reaching up to grope at her tits, they're warm in this summer heat, even when she never wears a shirt. He rubs her nipple and she moans, and Loki slips his hand into his own boxers and starts stroking his t-dick.
Sooner than later they've all forgot about the movie and Thor has them lying on top of each other rubbing their clits together and making out as he moves to fuck both of their warm, sopping wet pussies, fucking into lokis, then moving on to Sylvie's, then back again. Eventually they're all cumming all over each other and Thor makes Loki and Sylvie clean everything up with their tongues, and making them clean his cock together, both of them sucking and licking and drooling all over his cock until he's hard enough to fuck them again, but this time he makes them take turns riding him, edging themselves.
Eventually Loki just rubs his little t-dick until he squirts all over big brother's cock and Sylvie humps his thigh until she cums as well, dripping all over his thigh.
Then, they take a real shower and cuddle up in bed together while Thor reads them a bedtime story
And just the atmosphere of the Appalachian wilderness throughout everything. Ohhh my. I love the applachian wilderness as a setting for both gothic horror elements to take place as well as just how beautiful and peaceful it can be.
And the angst I could write into this, like how the summer has to end at some point, and Loki and Sylvie have to go back to school. Loki has to go back to being the weird trans boy who's in love with his sister and Sylvie has to go back to being the weird girl who's in love with her brother. Except now they're both in love with not only each other, but also their older brother. They have to go back to reality, and can't stay with big brother forever in his double wide in the woods, hunting and fishing and watching movies and reading stories forever. They can't spend their whole lives reading bedtime stories by the lake while fighting off mosquitoes.
They both have to face the fact that when Odin finds out, he'll have them separated. He'll have them never see each other again, so it doesn't harm his reputation. He can't have incestuous twins for children. Loki being trans was bad enough for his reputation and his business.
But maybe they stay in that trailer in the woods, catching lizards and hunting deer. Maybe Frigga tells Odin Loki and Sylvie went to a boarding school, and soon they'll be at college. Maybe nobody ever finds out about anything, and they can stay in that trailer in those woods by that shimmering lake forever. Just the three of them.
