Percy catches them one day, Fred and George, he had admitted to himself long ago that he loved Quidditch, but his brothers couldn't know that, he had to work. So, he went down to the changing rooms, it was late at night, (so no one could see him) and, he guesses, that's why they were so careless.
What Percy saw as he silently opened the door to the change rooms surprised him. He expected to be disgusted, but, instead, he was already half-hard.
Fred was shirtless and pinned against the lockers by George who looked like he was about to rip Fred's nipples off with his teeth. George was tugging, licking, sucking and, sometimes, even biting, Fred's nipple, he was tweaking the other with his free hand.
Fred had his eyes closed, as did George, and was letting out erotic moans as George's hand slipped past his waist and came to rest on the other's trousers waistband. Slipping his fingers around it, he slowly tugged them down until they fell to Fred's ankles (that had no pesky shoes or socks to stop them) and he kicked them off, running his hands over George's chest as he did so.
Fred let out a particularly loud moan as George let his hands work Fred's hard-on through his boxers, while still sucking on Fred's nipple. George stopped suddenly and looked at Fred mischievously, Fred all the while whining at the lost contact.
"C'mon Freddie, I'm being nice tonight, you're not just 'gonna leave me hanging (or should I say stiff and dry?)" He winked, "are you?" Fred then got down on his knees and pulled down George's pants, to reveal a large tent (Percy thought George must have had a very big you-know-what if his hard-on was that big, the biggest Percy had ever seen).
Fred then started to tease George and sucked him through his boxers, George moaning all the while.
"Okay, okay Freddie, enough teasing, I can't take it. I wanna fuck you, right now!" George gasped out, in-between his moans.
Fred stopped and stood up whispering in George's ear, so that Percy could only just hear, "Well then, take me, and fuck me good," He also said something else, but it was too quiet for Percy to hear.
By this stage, Percy was harder than he had ever been, even when he was with Penelope Clearwater. They both pulled each other's boxers off and George slowly pushed his erection inside Fred.
"Always cut right to the chase, don't you Georgie?" Fred said, half laughing and half wincing from the pain. George leant in and kissed him, a gesture that meant he would try to be careful (this time at least).
Percy realised he couldn't take his eyes off, and that if he stayed much longer, he was bound to be spotted, so he put an invisibility charm upon himself. He slowly reached his hand inside his pants to meet his throbbing erection that was just begging for attention.
Fred had gotten used to it and George was now pounding into him at a steady pace, moans and, grunts from George's part, could probably be heard from the castle, they were just that loud. They didn't care if anyone found them.
George leant down yet again to kiss Fred as he started going faster, signaling that his release was to come soon, he started to pump Fred's hard-on in-time with his thrusts. They both started moaning louder, George couldn't take it, he let go of Fred, resting his hands either side of him on the locker and (if it was possible) started going faster.
Percy began stroking himself in-time with them as well, he tried to stick one of his fingers inside himself, but it felt uncomfortable and wrong, so he didn't do it again.
"Aah! Ah, FRED!" "GEORGE!" They both said at the same time as they came at the same time, panting, trying to regain their breath and energy.
Percy came just after them, letting out a small moan he hoped they hadn't heard.
"Well George, I think someone enjoyed it as well," Fred said, opening his eyes, looking towards Percy. But, it was impossible, he had put up an invisibility charm!
"Yeah, I think he did. You know Fred, I think it really did come in handy, that book of yours that had the counter curse, for the room; so that anybody in the room would automatically reveal themselves, and if they tried to put up the invisibility charm, they couldn't," He said, still half panting, and laughing in-between.
They both pushed themselves from the locker and made their way over to Percy, holding hands. They came to a stop and both said, "Do you want to 'play' with us big brother?" at the same time.
In an instant, Percy was hard again.
Hope you enjoyed! I loved writing this! :)