Ordinarily I'd ask the author's permission before posting the story here, but I have no idea if he's still active on any other site or how to get in touch with him

The story is too good not to share though, so here it is:
(It was originally written in french and translated either automatically or by other users on the respective sites)
Chapter 1: The Pool
Remi was impatient. Tomorrow he would go on holiday to the south of France and he could see Juliette again. Juliette was the daughter of his parents' best friends and they often went on vacation together. She was 16 years old, tall, dark, dark-eyed, mischievous. He was under her spell. He had often dreamed of going further with her, but he was very shy, a little timid, while she was livelier, and more mature. When they were together, she treated him a bit like a child while she acted as an adult. But this year would be the right one. He was in second form at Middle School now, he had grown at least 10 cm this year, had gained some muscle, and had almost no acne pimples. He felt he was a man, and Juliette would be impressed.
The next day he took the train to Paris for Marseilles. His parents would join him next week. He would just be staying with Juliette and her parents. The best holidays possible ...
On his arrival, Juliette and her parents came to fetch him, but they were accompanied by another boy - Eric.
Eric, was the son of Juliet's parents' friends, He was almost the physical opposite of Rémi. As much as Rémi was brown, tall, a little shy and awkward, Eric, was small, with the physique of a child, but very lively and not shy at all. After some time Rémi was reassured, Eric was in 3rd grade at High School, and was just 15 years old. Juliette would certainly not be interested in a little boy, she would prefer a man like Rémi.
Arriving at the Mas, the 3 were immediately at the pool. It was not only Rémi who had grown up, Juliette had developed breasts and Rémi had a hard time taking his eyes off her. Eric, turned out to be a real clown, chaining jumps in the pool, fun games, and even making straightforward jokes on Juliette's breasts. Rémi did not know how to position himself: He found Eric very funny, but also a little annoying. He wanted to appear adult. When Juliette came out of the pool to sunbathe, Rémi settled beside her and they were able to start chatting. She found Eric very funny, but really a kid, and she told Remi that she found him changed, more mature. Remi savoured her sweet words.
Meanwhile Eric was playing alone and began to provoke Rémi: "Rémi stop hanging about there!!! Come play!!!" Rémi would have liked to have played with Eric, but he wanted to stay with Juliette even more. "Rémi I bet you cannot beat me in a race," called Eric. "I want to see that boys!" said Juliette. "Come on, come on, Rémi", said Eric, "the loser must show his butt!" "Not even in a dream!" answers Rémi laughing. "But I'm sure you'll win," Juliette said softly.
It is too much for Rémi, who plunges into the pool and prepares for the race. Eric proposes that they do 4 lengths. Juliette is the referee ... And here we go. Rémi wins fairly easily, after all he is the bigger one. "Not fair", said Eric, "he's bigger!" "It's you who wanted to", answered Juliet, "Go on, show us your butt!" "Double or quits?" implores Eric, "We should do a contest to see the one who remains the longest under water, if I lose I go around the pool without my swimsuit."
Remi is blown away by Eric's proposal, he would never have dared. He does not have time to answer before Juliette says: "Okay, leave or double". Rémi does not dare to protest, and in addition, he sees the opportunity to ridicule Eric a little, to lower him to his rank as a little boy. The two boys dive under the water, and clearly Eric is doing the maximum to win, but Rémi holds good and finally Eric is forced to come up to breathe. Remi joins him almost immediately, but barely breathless. He comes out of the water, and goes to see Juliette, who is delighted. She whispers in his ear: "Bravo, Rémi, you are the boss. Eric will certainly be less proud now!". Remi was blushing slightly, his cheeks reddening. "Come on, Eric, a little turn in the nude", Juliette yells, being careful that their parents didn't hear her. Eric comes out of the pool, sheepishly, and moves to the other side of the pool, removes his swimsuit. He puts a hand in front of his genital to hide them, and starts to walk around the pool. He has white buttocks, smooth and without a hair like a baby. He uses only a single hand to hide his sexual organ, which certainly means there is not much of them. He is really young, as Rémi says.
"No hiding things, take your hand away," said Remi. "No, no it was not mentioned in the rules", answers Eric. "He's right, he can keep his hand," for this time, "Juliette said as a justice of the peace. Once the round is over, everyone is a little red and excited. Eric for showing himself like that, Juliette very pleased with the show, and Rémi, who says he never could have done that, and doesn't understand why he feels excited. To bring down the fever, nothing like a good taste. Their next words are spoken quietly (the parents are not far away). "You'll owe me a revenge" said Eric. "Don't suggest it, I'm always the strongest," Rémi says. "Be careful, next time you will not have the right to hide behind your hand," warns Juliette.
And the 3 young people laugh frankly at this idea. "Everything is getting better." says Rémi to himself, "Eric is finally funny, and is still a child, and Juliette has never been so close to me".