Mark was laying awake in bed and couldn't get to sleep. He didn't feel lonely anymore, with Max and Zack stuck to his sides... but that was the problem. Zack had his head turned to Mark, and was snoring right in his ear, and breathing on his neck. He couldn't turn to face the other way because Max was sleeping with his head pressed right up against his, with their cheeks pushed together. Max was sound asleep, but at least he wasn't snoring away like Zack.
Mark was pressing his eyes closed, hoping he would just drift off, but any time he got even remotely close, one of his brothers would move and tug on their joined bodies, and bring him back awake. Mark was about to give up, and just split away from them, when Max used their left arm, and brought it up across their chest, rubbing Mark's side. Max had turned his head a bit, and was now facing Mark, and mumbling in his sleep. "Mmmm... Luke..."
'He must be dreaming' Mark thought. He tried not to think about his brother grabbing his chest, and tried getting to sleep, but when he felt Max gently kiss his cheek he felt a tingle between his legs. Mark lifted the covers and looked down at his and Max's shared cock slowly getting hard. 'Well... his dream with Luke must be going good!' Mark smiled, he turned his head to face Zack, then instantly turned back to Max once he saw Zack's wide open mouth, and felt a breath of hot air.
"Luke.... Luke...." Max mumbled, giving Mark a light kiss on his neck. Their cock was now rock hard, and Mark was now wide awake. He contemplated what to do for a few minutes, then he slowly grew his arm our of Zack's back. As soon as he could reach, he began working the shared erection, as gently as he could. Max had his face glued to Mark's again, and let out a soft moan. Mark giggled to himself, and began going faster.
Their chest was heaving with every breath Max took. His eyes were still shut, but he had stopped mumbling, and was now panting. Mark closed his eyes too, and tried to imagine he was stuck to someone else. Ethan came to mind first. Mark was trying to remember their time spend joined at the chest. But as he continued to think, Ethan slipped away, and Dean came up instead. He didn't know what it meant, but Mark smiled, the thought of Dean seemed to help better.
"L-Luke?" Max asked, coming awake from the feeling in his dick, and the subtle movements Mark was making.
"No... Mark..." Mark said during breaths.
"What's... going... on?" Max had lifted the covers and looked down, "Dude... really?"
Mark stopped and stared at his brother, "Well... we were about to cum, but I guess you just want to go back to sleep..." Mark could see the grin on Max's face as he shook his head. Mark grinned too, and started once again at their shared penis.
Both of them were now moaning and grunting, and trying to trust themselves into Mark's fist while it moved. Mark and Max turned to each other at one point and shared a kiss that was only broken by the need for air. When they finally did cum, they weren't expecting it. Their dick was pointed at Zack, from all the weird moving they were doing, while trying not to move Zack too. The load shot out, and landed up and down Zack's back. Mark instantly covered his mouth to stop from laughing, but Max couldn't hold it in.
Zack lifted his head and opened his sleepy eyes, "Hey... what's going on? What's so funny?" He tried to lift himself up, then remembered that the three of them were all joined. Instead he propped himself up with his left arms, and stared at his brother to his right. "Guys? What's going on? I'm trying to sleep and..." Zack could see Mark and Max's shared dick, and the line of cum from it's tip, up along his back. "Ew! That is disgusting! Can't you save your twincest for when your along... together?!"
Max was still chuckling away to himself, and Mark had a big goofy grin, "Calm down Zack. We'll clean it up! Just enjoy the afterglow for a moment."
Zack was about to protest, but found himself smiling too. He reached around with his left arm, grabbed the sheet he had kicked off, and wiped down his back. "Maybe next time you could wake me up?"
"Ok little bro!" Max said. He reached over with his left arm, and patted Zack on the shoulder. "Next time for sure!"