Shhhh he'll hear you Thorin sighed, too tired to even investigate his nephews' giggling. When they had retired to their rooms earlier than usual, he had assumed they'd be up to something.
"If you two are planning on playing a joke on me, you will not be pleased." More giggling erupted from their room and Thorin frowned. He debated going over and telling them to quiet down, but he knew they wouldn't listen. He sighed again, even louder, as he slouched deeper into his chair.
Did you hear him? He sounds like Balin now! Thorin jumped from his chair.
"I do not sound like Balin!" Thorin yelled. He was answered with more giggles. Thorin made up his mind. He walked through the hall outside their room and stood silently, waiting for a good moment to burst through the doorway and surprise them. He stuck his head slowly out to peek into their room and his heart stopped.
All he saw was blonde and brown hair attached to two heads that should not have been that close. He noticed Kili's fingers grasping at Fili's braids as he pulled him closer. Fili soon took control and began working his fingers across his brother's stubbly face and into his flowing hair as he kissed him lightly. Thorin nearly fell over.
"If only Thorin was out," sighed Fili as he broke apart for air. Kili smiled as his brother's lips found his again and he felt hands on his chest, slowly stroking upward.
"Fili! What are you doing?" The boys jumped apart, Fili's lips leaving his brother's more rapidly than Thorin could believe. Kili sat on the edge of their bed, staring at the floor.
"Oh hello, Thorin." Fili whispered, searching for a place to look besides the accusatory eyes of his uncle.
"I- I need to take a walk." Thorin stumbled away, ears ringing with the sounds of giggles. But they're brothers! His thoughts screamed.
Thorin knew they had not stopped. Could even imagine them continuing. Maybe even wanted to imagine it.
Kili would be unsure if they should, but Fili would grasp his hands and tell him its all okay. Fili would slowly kiss his brother's fingers and move up his arm until he reached Kili's lips. The soft, pink lips would part slgihtly, and his eyes would close as Fili nibbled on his brother's lips. Fili would continue stroking his chest, hand slipping lower and lower until-
"No!" Thorin yelled aloud. "Why do these thoughts plague me?" Thorin was so consumed with his musings he had not realized where he stood.
Because you're gaaaaaayyy Fili whispered out his window above Thorin's head before collapsing into a fit of giggles and pulling Kili on top of him.