All characters over the age of 18.
In case you've not read earlier chapters, note that the mother's friend is termed "aunt" as was once common practice for family friends. It would have been tedious to use inverted commas for "aunt" throughout!
*****
Neither of them spoke about it, but they were both conscious that the days were rapidly passing and that she would soon be leaving, to move into her new house.
As she worked and lived about sixty miles away, it was inevitable that their times together would end, either with a grande finale or simply fizzle out. The distance was the major issue. Although only sixty miles from his mother's home, he had no transport of his own, and in any case he was away at college for much of the time, a further hundred and seventy miles or so from her home town.
The other issue was the difficulty of maintaining discretion. It would arouse neighbours' suspicions if a young man turned up reasonably often to visit a woman twice his age. It wasn't viable to stay overnight, and less viable to close blinds or curtains at her home during the day. She was also due to return to work once she had moved in.
Realistically, their affair was drawing to a close.
From her perspective, it was perhaps as well. She hadn't been in a relationship for a while, and she felt it was time to try to change this. Besides, it was becoming difficult to act normal in the house and not to give his mother grounds to guess what was going on. It was difficult for Sue and her friend's son to avoid undue eye contact or other body language that might give the game away. Sue had moved away eight years ago, but Angela, his mother, was still her closest friend. Sue wouldn't want to hurt her, or to lose her friendship.
There was no denying that the limited time they had remaining together intensified their desire.. They had shared slow, lingering foreplay and after-play as well as full-on sex while his mother was at work. They had also enjoyed fleeting gropes, fumbles and flashings behind her back when she was at home.
__________
He awoke some time before his mother went to work. She was commencing her spell of morning shifts. He dozed off again, and half-awoke to the sound of the front door closing and the car engine starting.
A short time later he heard Aunt Sue stirring and going to the bathroom. A few minutes later she returned to her room. As usual, he was partly hard awakening. His anticipation of sex with his mother's friend made him harder still. He decided to take a shower.
He didn't bother bolting the bathroom door behind him. Having taken a pee he stepped into the shower cubicle and stepped under the shower head.
After a few adjustments to the thermostat, he was content, and began to lather himself with the shower gel. He was washing his genitals when he was conscious of the bathroom door opening.
Through the wet and steamed glass screen he saw her outline. He felt oddly embarrassed to be washing his private parts, and resumed washing his chest and armpits. He saw her plum coloured satin robe slide off her narrow shoulders and off her petite body. His member stood to attention in response.
She felt a little surge of delight at spotting his mother's dressing robe hanging on the back of the bathroom door, another reminder of the furtiveness of their times together. She stepped towards the cubicle door, swung it open, and stepped inside to join him.
Despite their having had sex on a number of occasions, he still gazed longingly at her, his eyes sweeping over her naked, petite body. Her mature, slender body itself enthralled him, and so did the way that the water jetted onto it and streamed down it. Once more the eagerness in his eyes made her feel sexy and desirable. It was also empowering to note the effect she was able to have on a lad young enough to be her son.
He gestured slightly nervously towards the window. Although made of opaque glass, it was open to let out the steam.
"I'm not sure this is a good idea, Aunt Sue," he said quietly, in case the next door neighbours should be outside and overhear. "Someone might see that there are two people in here, not just one..."
"If we stand close together nobody will guess," she countered.
He sensed that she was right, but the risk of being seen and of their activity being guessed, however unlikely, excited him. She stepped closer and put her hands on his waist. She looked up into the eager, youthful face of her best friend's son and pursed her lips, encouraging him to kiss her, and wanting him to make the first move. He stooped and kissed her on the mouth, his lips moulding against hers. He placed his hands on her slim waist, then, as their kisses became deeper and more passionate, his hands swept over her narrow back and fondled her firm bum cheeks, savouring the feel of her smooth, wet skin.
They both relished their mutual kissing, deliberately avoiding touching each other's genitals, content for now simply to enjoy their French kissing. He even avoided touching her breasts, too, other than holding her close against him. From time to time they swung round so that each could get the benefit of the warm, cascading water, and their synchronised movements as they did so seemed very erotic. The jets of the water stimulated her nipples and made them hard.
She nibbled his ear with her teeth and kissed his neck and throat, admiring the feel of his young body as she caressed him. Whilst he wasn't muscle-bound, he wasn't over-weight either, and his body was well-toned in a natural way. She looked down at his erection, trapped against her belly, and she pressed against it in gentle squeezing movements.