*Thoraopagus - the most common form of conjoined twin, comprising 35-40% of all conjoined cases.

Dana and Diana didn't get out of the house very often. Even growing up, they'd never gone to school like other kids, instead having professional private tutors. They were both brilliant, high IQ's, very talented, very creative. College was a possibility now that they'd turned eighteen but that seemed unlikely for them. Dana wanted to study engineering and Diana wanted to pursue fine arts. Normally, this wouldn't be a problem for ordinary sisters, but in their case, it was. Dana and Diana were joined from just below their breasts down almost all the way to their hips. Siamese twins.

Looking at them from across a room, a man might only think he's seeing two beautiful young women standing very close together. Intimately close even, and that would cause a stirring of interest. One was the slightest bit taller than the other, probably no more than an inch, and a little heavier. She wore a serious look that spoke of strength and self-confidence. The smaller one was a bit more delicate, wistful, trusting. The closer you got to the pair, the clearer the resemblance became. They would pass for identical twins, you'd think - if you didn't know the truth yet. Both had shoulder length, white-blonde hair, fine, sculptured features, high cheekbones and unearthly green eyes with an elfin tilt at the corners.

They had four beautiful tanned arms, four well-proportioned strong legs, two firm butts and two normal, albeit virginal sets of genitalia between their hard thighs. They'd been alive long enough to learn how to stay healthy while sharing a common stomach and liver and dealing with Diana's weaker heart. Dana's heart was the strong one and seemed to pump most of the blood for both their bodies. Because of these three complications, surgery had never been an option for them. Diana would have surely died.

Dana was quite protective of (whom she called) her "little sister", though she tended to do more than her share of bossing her around. She was the more academic of the two and taught Diana many things. Including her first lessons about sex.

Their parents had supposed they'd never really have a sex life and had sorely neglected their education in that area. Dana, on the other hand, was fascinated with it. Some nights while Diana slept - her legs wrapped over her big sister's and her head on Dana's shoulder - Dana surfed the internet for all the information she could absorb.

They'd first begun to masturbate much later than normal girls. It was amazing, the feeling they got! Dana could feel Diana's orgasm as well as Diana could, and vice versa. Cumming simultaneously was a mind-blowing experience and it became even more fun to touch each other down there. They both had soft, fine downy hair that got so wet with their playing. Was it incest or masturbation? Dana giggled at that thought, licking her sister's juices from her fingers.

It took Dana a lot of coaxing to get Diana to agree to have sex with a man. Dana herself had been dying to try it while Diana worried about how the man would feel about their unusual, shared body. Finally, after speaking online to a young man for about three months, they set up a meeting at a time when the girl's parents would be out most of the night.

He'd known of their condition before they'd invited him over but he assured them he was fine with the whole situation. However, at the sight of their naked flesh joined in a most unnatural way, he'd made an exceptionally cruel joke and fled.

That left Diana in tears and Dana angry with humiliation. She wanted to feel what sex was like so badly but this was enough to scare her back into silence, for awhile.

The desire continued to gnaw at her. Her sister's pretty fingers moving in and out of her pussy just weren't enough, but she'd be damned before she'd let any man near her again. And poor Diana wouldn't even speak of it.

Dana managed to keep Diana interested in sex with their sisterly games. They ordered a little dildo from a company online and kept it secret from their parents. Dana found that - strangely enough - she could feel more of the sexual pleasure when she made Diana cum than when Diana played with her. The deeper into her sister's tight pussy she rammed the dildo, the more she herself could feel it. That was what first gave her the idea.

While Diana slept in her cuddling position, Dana searched for another man to invite over, being even less selective this time. It would be very different. She told him exactly what she wanted and he eagerly agreed to it. She just hoped he wouldn't turn out to be as squeamish as the other guy had been.

Dana thought she should feel guilty about her plans, and rightly so, but if she'd just come out and asked Diana, the answer would have been no. So, she just chose to skip that formality.

The following morning after their parents had gone off to work, Dana insisted on a swim, an activity they both enjoyed. All their clothes had to be custom-made or at least altered, except their bikinis. It was the only way they could express their different tastes in clothing. Diana's was white, soft lycra and Dana's was wild with color, reds, blues, yellows - easy to spot from a mile away.