Rachael was sat at the back of the early morning bus as usual, on her way to sixth-form college. Earphones plugged in and reading from her phone, she barely noticed the lady sit down next to her.

This morning, her favoured college clothing - jeans and tee-shirt were all in the wash, so she had hurriedly pulled on a pair of tight white seamless leggings and a long belted jumper reaching her thighs.

Dashing out the door after breakfast, she just caught sight of herself in the mirror from the rear and realised that her choice of black lace panties showed through the leggings rather too provocatively.

Too late to change, Rachael just pulled down on the hem of the jumper and hoped the coat hid her embarrassment until she could get to college to swap the black panties for a spare white thong she always kept in the locker.

The bus had only recently installed free wi-fi and Rach was delighted to find that her favourite porn site, which she had recently re-joined, was not only unblocked but fairly quick. She could now use the journey time to catch up on all those stories that David had written for her and think up some suitably sarcastic comments that she wasn’t really ‘like that’.

She had to admit that some of the images conjured by the stories were making her a bit damp and the unusual panties were sticking between her legs. Almost without thought, her right hand snaked down inside the leggings to adjust the crotch to be more comfortable against her moistening pussy lips.

This morning Rachael had moved on to re-watching one of her favourite porn videos called Tits Suspension. This showed an attractive large-breasted and collared redhead being bound and raised by the ropes around her tits. The girl’s Master applies clothes pegs and weights to her nipples, then swaps the clothes pegs for proper nipple clamps on a heavy chain.

Rachael couldn’t resist moaning slightly along with the girl in the video as the Master finger-fucked her to a painful conclusion.

[Note for connoisseurs of the art there is another, longer video called Breast Bondage SMG on the xhamster mobile site - that is exceptional - clearly lifting the screaming brunette babe clear off the floor for several seconds].

Rachael was just checking on her shiny new butt plug - a 17th birthday present from her Dom, when she became aware of the lady sitting beside her on the bus, as their thighs briefly touched: “Oh Mrs Brown - how lovely to see you again.” Rachael rapidly paused the video and removed her hand from her crotch, wondering how to hide the glistening juice on her fingers.

Mrs Brown had been Molly and Rachael’s games teacher at school many years ago and like most girls, in the class, they’d had a crush on her. Tall, athletic, blonde spiky hair, married - she had been out of reach to all except the most determined pupils; but now seen twice within a week.

“It was lovely to meet you and Molly again on Saturday in that restaurant - was that other gorgeous redhead Molly’s mum with you?”

“Yes - Justine - she took us out for a lovely meal and then back to bed. Oh, I’m sorry - did I actually say that out loud?”

“Yes you did - that’s OK - I had something rather similar in mind,” she squeezed Rachael’s thigh “and I loved those matching leather collars - are you all subs?”

Then she held Rachael’s sticky fingers, inhaling the intoxicating scent, “may I?”

Rachael looked around at the other passengers on the bus - none seemed to have noticed the blatant seduction on the back seat. Her nipples hardened against the smooth woollen jumper as Mrs Brown sucked on her fingertips and then suggestively licked down between the open V of her fingers.

“You taste divine darling - I can’t wait to sample your delights directly - so tell me who else is a sub?”

Rach wondered how much to tell: “er yes, Justy and I are, but Molly has pretensions towards becoming a Dominatrix. Sam is teaching her how to switch.”

“Oh, wonderful - I’ve noticed Sam in several of David’s stories - you are very lucky to have such an experienced Dom.”

“You read dasx2 too?”

“Oh yes - all my friends love Ms Jones, the Sex Ed teacher - she’s so lucky to have that junior sexbot for the children to play with and watch their little penises inside her.”

“Not really my style,” replied Rachael, “I prefer playing with real women”

“Then you both must come over Sunday afternoon - wear those tiny netball skirts if they still fit. Don’t worry about Mr Brown - he’s a real sweetie - he’ll just watch and take a few photos.”

The games teacher gently stroked the side of Rachael’s breasts, “he loves to see how his little girls have developed,” she twisted a nipple, “and these have developed very nicely.”

Mrs Brown handed Rachael a business card, “there’s the address - gotta go - this is my stop.”

Intrigued by the name ‘Jade Brown Specialist in Water Sports Therapy’, she just managed, “Bye - I’ll be sure to ask Molly - she’ll probably want to try out her new latex gear.”

At College:

Molly found Rachael at the coffee machine, pushing her up against the wall and inserting two fingers, “who’s been a naughty girl then - cumming without permission?”

“Sorry Miss” - Rachael couldn’t bring herself to call her best friend from childhood ‘Mistress’ yet - but the time was approaching.

Rachael tried closing her legs to stop her panties from getting any damper - Molly reacted by inserting a knee to hold her sub’s thighs apart to permit a deeper cuntal inspection.

“We can’t have this - you’re dripping - you slut and it’s only 9 o’clock. What have you been doing?”

Rachael tried to explain the tit suspension video on her bus trip and showed Molly the business card, “guess who touched me up on the bus today - only Mrs Brown - our old games teacher.”

“Water Sports Therapy? - I guess that doesn’t have much to do with swimming - you say she wants to play with us on Sunday afternoon?”