"Ugh you guys are gross," Wendy scoffed, passing her brothers in the hallway. 

Iggy and Larry were casually holding hands in the corridor outside their bedrooms. The two weren't shy about their actions around the others, despite such a relationship being unusual between brothers. Ever since the koopalings hit their teens, they've all noticed spikes in their hormone levels. While the others remained silent about their changing feelings with growing up, Iggy and Larry were a bit different. They gravitated to each other in recent years, eventually sharing their first clumsy and curious kiss earlier that summer.

"Pfft, what a jealous bitch," Iggy mumbled. The green haired koopa turned his head and clenched his teeth. 

"Seriously," Larry replied. "It's not like we're bumping shells right in front of her."

An evil grin grew across Iggy's face and he turned his head. "Maybe we should."

"Huh?" Larry blushed, surprised by the suggestion. 

"I mean, if she wants to complain about us minding our own business, then maybe we should give her something to complain about." Iggy shrugged and pushed himself off of the wall. Letting go of Larry's hand he placed it instead on the wall next to the younger koopa's head. "If we use your room tonight she'll be forced to hear everything through the wall." 

"Everything?" Larry replied, sarcastic. The two of them weren't exactly loud in the bedroom. If anything they were usually almost silent with the exception of a small moan. "So, nothing then?"
Iggy leaned next to him, and whispered something to the younger koopa. Larry's blush increased to encompass his entire face. His jaw dropped and he covered his groin as he felt his boyhood twitching in his slit. Pulling his head back Iggy looked at his flustered brother waiting for a response. 

"Y…you…mean?"

"Unless you wanted to try it the other way around?" 

"N…no that's not what I'm… I just thought…well…" Larry wasn't quite sure how to respond. Though the two of them were a little intimate, it never went past oral before. They both were interested in more, but agreed to wait until the timeline felt right. Larry wasn't sure if this was the right time, but his older brother was hard to resist. 

"Pffft, you're so cute when you're caught off guard," Iggy chuckled, then leaned in and kissed Larry's snout. "Just think about it ok?" He walked off and waved at him, "I'll see you tonight."

… …

"Ah that's better," Larry sighed, stepping out of the shower. It was a long day of work at the castle and he was eager to relax. 

The steam billowed out of his bathroom as he exited the small area and into his room. Ever since Mario destroyed their castles, the Koopalings took up residence with Bowser. It was a little crowded sometimes with everyone sharing the same place, but luckily Bowser and Junior kept to themselves on the upper floors, leaving his adopted children in charge of the smaller minions. 

Larry's room was at the end of the hall, with Wendy's room being the first one after his. Iggy's room was closer to the other side making it slightly less private. Not that it stopped them from using the space for their evening fun. However, for the first time, Larry was hosting and the younger koopa was a bit nervous. 

A knock on his chamber door caused the koopa to jump. He was still naked from his shower. Quickly grabbing a pair of boxers, he slid them on covering his slit area. 

CREEEEEEK

The door eased open and Larry was greeted by his brother. The older koopa was in a silk bathrobe, loosely held together by its tie. Iggy's shell was noticeably off, as the robe hung down on his shoulders. Glancing up and down Larry's body, Iggy smiled and nodded. 
"Looking good Larry. So did you think about my offer?"

"Uh, yeah, come in!" The eager young koopa replied. He stepped aside letting his silk clad brother into his room, then shut the door tightly behind him. Turning around, Larry was surprised to see Iggy's robe drop to the floor. The green haired koopa was facing away from him, giving him a clear look at his tail. 
Instantly Larry could feel his dick peek out from his slit and touch the cloth of his boxers.

"Like what you see?" Iggy asked, shaking his hips from side to side. 

Larry stepped forward and grabbed Iggy's hips, pulling them against the front of his underwear. "Ungh!" The younger horny koopa grunted as he grinded his growing member against his brother. 

"Hehe," Iggy laughed, reaching to his own slit and rubbing along it with his fingers. "Doesn't take much to get you excited." He pulled away from Larry's grasp and headed for the bed. Stepping onto the mattress with one knee, he turned his head to invite his younger brother over. 
"You coming?"

Larry quickly pulled his boxers off, and ran over behind Iggy. The older koopa lifted his tail and smacked his backside to entice the younger koopa further. Larry still couldn't believe Iggy had offered his tailhole first. His heart pounded knowing he was about to take his older brother's anal virginity. His underdeveloped teenage cock grew stiff out of his slit. It was a bright pink, about 5 inches long, and tapered to a sensitive point. Iggy's was already hard as well, but was another half inch longer. It stuck out from his golden scales, and was slowly leaking precum onto the bed. 

Though they didn't have any lube handy, as koopas their natural juices would provide adequate moisture for penetration. Larry again grabbed Iggy's hips and grinded against him. This time the younger koopa's dick slid back and forth across Iggy's tailhole, wetting it with his thin and slick juices. 
"Mmmmm," Larry mumbled, anticipating what was to come. Long had he dreamed of sex, but now his dreams were becoming a reality, and it was with his boyfriend/brother too! 

"Yeah, get me nice and wet!" Iggy said, starting to raise his voice. He wanted to be sure it carried enough that Wendy could hear them through the walls. "You've got a great cock bro!" 

"Ah, Iggy," Larry replied, face turning red with embarrassment. "I…I want this so bad!" He grunted, matching Iggy's tone and volume. By this point the older koopa's backside was dripping with precum and was ready for something more. 

"Me too, Larry. Come on, shove it in already!"

Larry pushed his hips forward slowly. His cock slipped past Iggy's tight tailhole, until he was fully inside. The two both let out a loud moan, as their bodies adjusted to the new and overwhelming pleasure. Iggy was so warm inside.I Larry could feel his brother squeeze the base of his boyhood, sending spikes of pleasure up his spine. Iggy on the other hand felt a constant tingling sensation in his entire lower body. The pressure inside him caused precum to ooze out of his 5 and a half inch cock, and onto the bed. After a minute of just enjoying their first time together, Larry began slowly thrusting in and out. 
"Mmrph. MMmrph. Ah!" Larry grunted, his brother’s tight tailhole, felt amazing as it squeezed and relaxed over and over with each thrust. 

"Ah, holy shit Larry," Iggy moaned. "This feels amazing. H…harder. Fuck me harder, bro!" 
That was all Larry needed to hear to take things to the next level. He quickly pulled out of Iggy and grabbed his brother’s side flipping him onto his back. With a frightening smile on his face he grabbed Iggy's hips, raising him into the air. Then in one swift motion, thrust his entire length back into the koopa's tailhole.
"Larry!" Iggy moaned, his hole stretched wide by the sudden forceful thrust. 
The younger koopa began pounding harder and harder into his brother. The bed creaked from the force of their bodies rocking back and forth. It wasn’t long before the headboard began slamming against the wall. Iggy smiled as he was sure Wendy was going to hear them now. 

"You like that you sick freak?" Larry said through gritted teeth. "You like your little brother’s cock up your tailhole?"

"Ah, YES! I love your cock bro!" 

Just as they had hoped the sounds of their bodies slamming against the bed and loud moans were more than enough to echo into Wendy's room. Despite her public attitude towards their relationship, she actually was hoping to hear them fooling around for her own amusement. After all, she was a horny teenager too. 

It seemed her plan had worked perfectly. She was hoping they would end up moving closer to her room if she acted irritated enough. Playing on her brothers' personalities, she laid the perfect trap for their egos to fall into. As her two brothers' voices grew louder and louder, Wendy grew wetter. Laying back on her bed, she was desperately fingering herself with two claws.
"That's it boys," she whispered to herself, "Keep going, I'm almost there." The sound of two male koopas mating filled her with overwhelming desire. It didn't matter that they were her brothers. In fact that actually seemed to turn her on even further. She pumped her claws in and out, while squeezing her clit with her free hand. 

Meanwhile, Iggy and Larry were nearing climax themselves. The sloppy sounds of Larry's wet cock sliding in and out of Iggy's tailhole echoed through the room. They moaned in unison, as the forbidden pleasures of mating with each other controlled every single movement. Iggy's cock pulsed, leaking precum all over his chest. 
"L…Larry. I'm…gonna cum!" Iggy moaned.

"M…me too! T…together?"

"Y…yeah.  Almost th…AAAGH!" Iggy's whole body tensed. His toes curled and he wrapped both legs tightly around Larry's back. Pulling his brother fully inside of him. His cock throbbed wildly, releasing his teenage cum into the air. 6 solid streams shot upward and splashed all over his body. 

Larry reached climax as the third stream escaped Iggy's cock. He closed his eyes and gripped the older koopa's hips, releasing his teenage cum. The hot liquid splashed deep inside Iggy's body, quickly filling him up. His brother's tailhole squeezed Larry's cock, milking out every last drop from his body. 
"Oh, hell yes!" Larry grunted, as the last of his cum dribbled out. He pulled his hips back, yanking his shrinking member out. Collapsing on Iggy's cum soaked body, he looked up at him and smiled.
"That was amazing bro."

"Huff, huff, yeah…you really were. I love you Larry."

"I love you too, Iggy. You think Wendy heard all that." 

"Hehe, I bet everyone heard that."

Little did they know, everyone HAD heard them. Their incessant moans and violent mating were heard all the way up the hallway. While Wendy was furiously masturbating, their other brothers were finding new pleasures with their own bodies as well. Some rubbed their dicks, while others fingered their tailholes for the first time. Though Iggy and Larry were the first of the koopalings to hook up, they wouldn't be the last. After that night their siblings would discover just how much fun, mating with each other could be.