It all stemmed from a couple of unrelated incidents, the first of which had happened some time before when Erin had just reached the age of consent and was exploring the fun of sex with all the unbridled enthusiasm of youth, even though living with her parents at the time meant that most of this exploration had to be done out of doors.
She and her then boyfriend had found a quiet piece of local forest and made love as usual in the romantically dappled sunlight that found its way between the trees. It was a mostly unused stretch of woodland but they still hadn't risked stripping in case they were interrupted and so, although she had taken her panties off, their clothing had otherwise just been pushed up out of the way.
Afterwards they had lain side by side, spent and panting from their exertions but smiling happily at each other, he face down on the forest floor and she still on her back, luxuriating in the feel of a cool breeze on her open thighs and her overheated pussy. She had felt his cum trickling warm from her vagina, cooling as it made its unhurried way over her anus, and she had shivered with pleasure at the sensation. It had been one of their best ever sessions, losing them both in the power and passion of their lovemaking.
Eventually when their breathing was finally back to normal they had tidied themselves up, she giggling at his careful efforts to brush leaf litter from his still damp penis while she shimmied her skirt back into place. Then, hand in hand as always, they had made their way back from the privacy of the woods to the public lane that had brought them there, and as they had stepped from under the trees she had glanced regretfully back - and that is when she had seen the man.
The man had been older, dishevelled, unshaven and grey haired, and scruffily dressed in dirty grey trousers and black jacket. He had been cupping a cigarette to his mouth and letting a steady trickle of smoke drift from his nose, completely relaxed and making no attempt to hide his presence. Where he had been standing was a little to one side but with a good view of where they had laid, and it was clear from his body language that he had been there for some while and had witnessed most, if not all, of their lovemaking. She had gasped and stopped dead in her tracks as she realised they had been seen, and that the voyeur would have been able to see right between her open legs. Her boyfriend had asked her what was wrong, but unable to tell him, she had shaken a nonexistent stone from her shoe and pretended nothing else had happened.
It wasn't that she had been too embarrassed to tell him, nor even that she hadn't wanted his potentially violent reaction to spoil the evening. No, the real reason was that the sudden knowledge that they had been seen had given her an unexpected and tremendous adrenalin rush, a buzz the like of which she had never, ever, experienced. Just knowing that her pussy had been exposed to a stranger, and a down-and-out stranger at that, had immediately given her a thrill almost as strong as an actual orgasm and it had shaken and confused her.
This new excitement had stayed with her and as soon as she got home she had gone straight to her room and masturbated, biting her knuckles in an attempt to quieten her overwhelming arousal. From then on she had often fantasised of someone watching her as she made love, masturbating frequently while wishing that a stranger could see her exposed pussy. With minor variations this had for a while become her favoured fantasy, far ahead of any other.
But then as the novelty had slowly faded and she had split with the boyfriend concerned, newer and more vivid fantasies took over, leaving the episode just a wickedly delicious memory in the recesses of her mind. And there it had stayed until a new incident brought the memory and its effects flooding back.
This time she and her new man had been in each others arms on the back seat of his car, parked in a quiet lay-by on the way home from an evening in town. It was another normally deserted spot, frequented only by couples looking for privacy and the occasional dog walkers destined for a local footpath, and it was their most often used place for a little quiet fun. As usual they had parked at the end of the lay-by furthest from the entrance to the footpath so that any walkers would naturally head away from their car, and so they had ignored headlights pulling into place behind them.
But this time things had been different. For some never understood reason the couple from this newly parked car were headed along the road rather than the footpath, and to do so they had needed to walk past Erin and Jason sprawled along the back seat of the car. By this time Erin's top and skirt had both been pushed up and Jason was sucking and licking her nipples while at the same time his hand massaged and fondled her pussy through the thin material of her pure white thong, something that the couple couldn't fail to notice.
Erin had heard them approach without actually realising it, and it hadn't been until their silhouettes appeared at the window that she knew someone was there. Even so, she was so turned on and so enjoying Jason's attentions that she had tried to ignore them, relying on the fading light to mask their activities and instinctively knowing that a sudden covering up would only attract attention.
But the couple had seen them anyway and had come to an involuntary stop, gazing through the car window in amused surprise at the lovers busy on the back seat. Jason hadn't realised that they had company and so he continued playing with her breasts and pussy, his fingers digging between her cotton covered labia, and without thinking Erin had opened her legs a little wider, letting him play more intimately and letting the couple see more clearly.
She had no idea why she had so instinctively reacted that way, all she knew was that instead of being irritated or embarrassed by the interruption, she had felt a wave of excitement run through her, a thrill just like the one that she had felt so long before in that stretch of woodland. She hadn't wanted her uninvited audience to go away, but to stay and watch, and she had observed them through slitted eyes, her heart suddenly pounding and her pussy lubricating copiously.
"It's been a long time since you did that with me."
The woman's voice had come suddenly and clearly through the car window and had alerted Jason to their presence. In surprise he had snatched his hand away from Erin's crotch and his mouth from her breast, causing her to automatically slam her legs shut and yank her top over her wetly erect nipples.
"We've got a nice warm bed these days." The man's voice had said. "Come on, leave them in peace."
Erin had lain back on the seat as they walked away, bewildered, frustrated and above all angry. Bewildered because she didn't understand her own feelings, frustrated at the abrupt end to her fun and angry both at herself for feeling the way she did and with Jason for reacting with such embarrassment. Why, she had asked herself, why did they have to speak and ruin things and why was Jason so damn shy? If only they had stayed until she'd actually cum it could have been an orgasm to top all orgasms.
Just as before, she had masturbated frantically as soon as she was alone in her room, and just as before this incident had become the foundation for many more solo fantasies, keeping her fingers busy with illogical regularity. The difference this time was that as time went by her fascination with the thought of being watched did not go away, in fact if anything it had become even more intense until it almost reached the point of obsession. She knew eventually that she would have to do something about it, one way or the other, and so one night she broached the subject to Jason.
"Do you remember the couple that caught us in the back seat?" She asked.
"Do I ever!" He replied with a wry grin. "Wrecked things that night didn't they?"
"It didn't need to, though. How did you feel about us being seen?"
He looked at her strangely. "Pissed off and embarrassed, that's how. How did you expect me to feel?"
"I don't know. Didn't it give you a kick?"
"Not half the kick I wanted to give them!"
"But didn't you get a charge from it?" She regarded him closely. "Because in an odd sort of way it turned me on."
"I always knew there was something strange about you."
He was smiling as he said that, but she knew he was being halfway serious and it was time to leave the subject behind. Even so, she couldn't forget it and the next week she returned to it.
"You know if we get caught being sexy again." She began. "Can we pretend we haven't noticed and see what happens?"
Jason looked at her in disbelief. "You're weird! I don't want people seeing me get laid."
She changed tack, trying a different approach.
"What if we saw other people doing it, would that get to you?"
"Maybe." He answered thoughtfully. "But it's still not normal, is it? So don't hold your breath."
That wasn't going to work either, so Erin gave up and nothing more was said by either of them, although it was noticeable that Jason chose a different, more remote place to park up for their late night cuddles from then on. Erin smiled inwardly at his obvious attempt to avoid any interruption, but all the time she was still wrestling with her own feelings and she didn't yet feel strong enough to make an issue of it. She was still caught between her natural shyness, her inbuilt morality, and the tremendous thrill that the two brief episodes of accidental exhibitionism had given her. No way could she be sure that she would be able to go through with showing herself openly to strangers even if she managed to persuade Jason to try, and so she let things rest, relying on chance to resolve the issue for her. It was not for another several weeks that anything more happened.
They had been to a midweek gig headlined by a leading local rock band, and the heavy, throbbing music had got into their veins, making them feel surprisingly randy, too randy for Erin to wait until they reached their out of the way parking spot. It had also brought those two exhilarating incidents back into her mind, perhaps now was a good time to push things a little.
"There's a parking spot about a mile on, Jason. Can you pull in, I need a pee."
The pee wasn't that urgent, but it was a good excuse to park up somewhere different for once.
Jason pulled into the rather linear car park that served a local nature reserve and parked close to the entrance, obviously intending to move on as soon as Erin had done what she needed to. That was not what Erin really wanted.
The ribbon of tarmac that made up the car park disappeared into the dark, with a line of parking bays to each side and the side to which Jason had driven bordering a small picnic area. Erin jumped out and disappeared among the trees to squat out of sight between two of the wooden tables strewn around the area, her return to the car delayed as she hung back out of the sweeping headlights of another car pulling into the park.