Kicking off his shoes, Sebastian Hart strolled unashamedly into his sister’s apartment, letting the front door swing shut behind him. Swerving into the kitchen, he rifled through the cabinets in search of a snack, seizing the last maple-syrup-flavoured granola bar in the box. Knowing how much those bars crumbled, he at least had the decency to take a plate with which to catch the roughly ten million crumbs that would otherwise be scattered throughout his twin’s home. As he ate, he slowly swaggered down the corridor towards his twin’s bedroom.

He saw no reason to hide his presence, or his casual filching of food. After all, he was a guest. He’d been invited. Even if his sister objected, there was little she could do about it - because he wasn’t her guest. He was technically staying with her roommate. And he would gleefully rub that technicality in her face whenever the opportunity arose. Annoying Sabrina was one of his favourite pastimes. It wasn’t as if she could kick him out - it was as much Phil’s apartment as it was hers.

Whenever Seb swung through San Francisco, he’d typically ask Phil if he could stay over. He didn’t exactly have other options - he didn’t know anyone in the city aside from them, and a few of their kinky friends. That afternoon Phil had taken him out for lunch, and once again agreed to let him spend the weekend. So now Seb had somewhere to sleep, and it was with an Irish hunk who also happened to be his sister’s roommate, fuckbuddy, and dominant. Phil and Sabby were far from exclusive, but it’d bug the tits off her if he and her brother hooked up - so they did, pretty much every time Seb visited.

He tiptoed towards Sabrina’s bedroom, giggling under his breath. He hadn’t caught sight of his twin elsewhere in the apartment, but he was sure he’d find her in her room. He couldn’t wait to see the look on her face. Sebastian rarely forewarned his sister about his surprise visits, and neither did Phil, because they both enjoyed her reactions too much.

Sure enough, as he flung the door open and called out, “Honey, I’m home!” he was met by Sabrina’s shocked stare from across the room, which quickly faded into an exasperated frown.

“Oh, come on,” she groaned. “What are you doing here?”

“Good to see you too, sis,” he chuckled, setting the crumb-coated plate down on her makeup table and strutting over to his twin.

“Look, man, it’s not like I’m not happy to see you,” she said in a slightly less hostile tone, grudgingly trudging across the room towards him. “It’s just - I can’t host you this weekend. I got shit to do!”

“Bullshit. I’ve seen your calendar, Sab, you’re free and easy.” He sniggered. “Well, you’re already easy...”

Sabby pouted, putting her hands on her hips. “Fine. I was just gonna spend the weekend at home with Phil. Y’know - just the two of us...?”

“Don’t gotta draw me a diagram,” he grinned. “But, uh, from what I hear, it looks like someone mighta changed his plans...”

She rolled her eyes. “Sebastian,” she sighed, putting the emphasis on the ‘as’ to make it sound like she was calling him an ass, as was her habit. “Do you have to...?”

“Yeah, I do, he’s hot,” he snickered, as he studied his reflection in the mirrored door of her clothes closet, which spanned one wall of the bedroom. “Besides, we’re family. We should share...”

“That applies to cartons of milk, not boyfriends!”

He arched an eyebrow as he brushed strands of blonde hair out of his eyes. “Boyfriend, huh? You guys get serious all of a sudden?”

“Figure of speech,” she said sulkily.

“Besides, you’re trying to pretend you don’t ‘share’ with your friends, like, all the time?” he teased. “Often in front of each other. And you’re finding even more buddies to bone at this hypno con next month...”

“It’s different with you - it has to happen right in front of me. I literally have no choice in the matter.”

“Yeah, and we all know how much you hate that,” he said drily, slowly tracing a fingertip along his collarbone. “Being trapped, unable to escape, forced to watch as your ‘boyfriend’ screws someone else. Especially your twin! I can’t imagine how much more humiliating that must be - seeing Phil choose your own brother over you, being stuck watching us fuck...”

As Sabby squawked and spluttered incoherently, Sebastian slid open the closet door, silencing her with a smirk. That mortifying mental image would keep her occupied for a minute, while he got changed.

One end of her closet was taken up by a handful of garments he could wear when he visited, which she complained about but obviously didn’t mind too much, given that she’d made no effort to remove them. She actually bought them for him in the first place, well informed of his size and style as she was. It was a source of comfort, knowing he had those clothes ready for him whenever he showed up in San Fran.

Picking out an oversized grey T-shirt and matching cotton shorts, he dumped them at the foot of Sabby’s bed. Sliding the mirrored door shut, he tugged his more form-fitting denim dress down past his sizeable chest, letting it drop to his ankles. He discarded his bra next with a sigh of relief, and made a point, as he often did when he bared his breasts, of fondling and groping them. Sebastian appreciated tits as much as the average man, but the average man usually didn’t have his own - whereas he most certainly did, and they were awesome. How was he to resist the impulse to play with them? He was only human, after all.

He glanced up at Sabrina, who glared back at him even as she bit her lip, clearly suppressing a whimper. “Stop that!”

“Make me.” He stuck out his tongue at her as he rubbed and pinched his nipples.

“You’re such a manchild,” she huffed.

“Well, that can’t be a surprise. I didn’t have a childhood, I had to live vicariously through yours.”

“Well that’s hardly my f-fault,” Sabby gasped, squirming at the overwhelming sensations as she matched his movements precisely, powerlessly playing with her own chest. “It’s not like I planned to absorb you...”

“Fair point,” he conceded with a snigger, relinquishing his tits so he could reach out and tap the thick pane of glass separating them. “But still, you can’t begrudge me having my fun when I do visit, can you?”

She smiled wearily, her reflected finger drumming against the inside of the mirror. “Does it matter if I do begrudge you, a little bit...?”

“Not at all,” he cackled, impulsively running his hands through his blonde bob. “It’s not like you can do anything about - geez, there’s so much hairspray in here I can barely move it.”

Sabrina rolled her eyes. “Oh, please. You exaggerate.”

“No, for real, it’s like a fuckin’ hard hat.”

He was exaggerating, but not by much. Showering would subdue the golden mane a little, enough that it’d fit under one of the assortment of wigs his sister kept for him, in a tub on the closet floor. He didn’t mind his hair, exactly, but it didn’t feel so much like his - it was the only part of his feminine body that actually gave him any dysphoria. He preferred to cover it with a short brown mantle, which felt more masculine in a way that suited him.

But he was in no real hurry to dress up his borrowed body the way he liked it - he was having too much fun messing with his twin. And his top priority was still to get decisively dicked down by Phil, who would be home shortly.

Whatever retort his sister was about to utter in defence of her excessive hairspray was interrupted as he flung himself backwards onto her bed. She let out a yelp as she was pulled down with him, but after that she was struck dumb once more, with Sebastian no longer looking in the mirror. Reaching for his hips, he slid his lacey black panties down his legs, which he raised up above him as he did so, bending and extending them as needed as he slowly removed his underwear. His ample ass was perched on the edge of the bed, presenting his pussy to an absent audience. Not even his sister could see his seductive movements right now, stuck as she was in the exact same position as him, staring at the cream ceiling.

Flinging his knickers aside, Seb ran a hand between his legs, and it came back soaked. Hardly surprising. Playing with his sensitive titties for a couple of minutes never failed to get him going, and besides which Sabby was clearly reacting the same way she always did to being imprisoned within her own body - with unbearable lust. Shuffling back onto the bed and shifting around by ninety degrees so he could plant his head on the pillow, he resumed groping his chest with one hand, while the other snuck back down to stroke his snatch, keen to ensure he was as wet and ready as possible for Phil. He owed him that.

Sebastian wasn’t trying to be cruel to Sabrina - he only teased her because he knew it turned her on, which, in turn, turned him on. He didn’t feel any malice towards his sister - although, it was true, she got to live the full life that he’d never had. He’d been lying dormant within her for her entire life, ever since she’d absorbed him in the womb, which, as she’d rightly pointed out, she couldn’t possibly have done of her own accord. And it wasn’t like he’d been suffering - he hadn’t had a mind or personality of his own back then. He hadn’t even known he was in there until Phil, intrigued by Sabby’s anecdote about her vanishing twin, found him submerged in her subconscious and woke him up, just under a year ago. Since then, he’d ‘visited’ roughly once a month, whenever Phil felt like reversing the siblings’ positions (as he had during his and Sabrina’s lunch date that day), putting Seb in control of their merged body and rendering Sabby a passive observer to his misbehaviour, only able to communicate when he looked in a reflective surface.

Sebastian had all of Sabrina’s memories, enabling him to effortlessly pose as her in front of anyone outside her hypnokinky social circle. But he preferred to be himself - to make a few temporary cosmetic changes, like the wig and the clothes, to make himself more comfortable in his sister’s skin - and to indulge in whatever whims took his fancy, after being denied that for 23 years. (Most of those whims were sexual, admittedly - he and Sabby had that much in common.) So he spent much of his time in the company of those who understood and gave him the space to be him - the aforementioned kinksters, namely Phil, Hailee, Milo, Irene, Lena, Charlie, and whomever else happened to be around during his brief guest stints. He was really hoping to spend some time with Countess Dafne this weekend - the buxom vampiress was unfathomably hot, and she had an enclave full of enthralled cuties he was eager to play with.

For the moment, though, he was perfectly happy where he was, lying on his back on the bed, with one hand massaging his boobs like stress balls while the other’s index and middle fingers were buried to the knuckle inside his boycunt. Gurning and gurgling from his greedy self-gratification, he glanced to the right at a similarly supine Sabrina, who was giving him her world-famous side-eye.

As he added another finger, his body spasming as his fingers reached right up to tickle that sweet spot deep inside, Sebastian grinned at his sister. Sabrina couldn’t stop herself smiling back.