The company had arrived at Beorn's house two days previously, and Kili and Fili had not seen very much of their uncle. Or their burglar, for that matter and they were somewhat concerned. Thorin had been severely injured in the fight against Azog, and there was only so much Gandalf could do.
So the pair decided to search for their uncle and when they passed an oak wood door and heard the unmistakable voice of Thorin yelping and whimpering, they burst through the door without hesitation. Worried that their uncle was in pain or danger.
Both wished they'd have knocked first.
There on the bed was their uncle, bare as the day he was birthed, on hands and knees being fucked by their burglar who alternated between spanking their uncle and wrapping a hand around the dwarf kings' cock as he buried himself up the hilt in his ass repeatedly.
Thankfully, neither Bilbo nor Thorin had noticed the two horrified dwarves in the doorway
The keening of their uncle as he begged the hobbit to fuck him harder and faster as his back arched made both boys blush to the roots of their hair and turning on their heels, they near flew from the room, shutting the door behind them.
They didn't stop running until they collided bodily with the soft form of Lasair, who took one look at their horrified faces and laughed.
"Let me guess, you walked in on your uncle and Bilbo?" She grinned as they paled to the point of looking like ghosts.
"It didn't happen. It didn't happen. It didn't happen. We saw nothing, absolutely nothing, they were playing chess, yes, chess." Kili was muttering to himself, and the part dwarf almost felt bad for the traumatised heir. Not enough to not nearly kill herself laughing at his expense though.
"Not funny, he, and then, oh Aulë, the noises! I'll have nightmares for weeks" Fili whined, burying his head into the crook of Lasair's neck, his beard tickling her throat causing her to moan softly.
"C'mon boys, help me up and we'll get some ale in ya" she offered, feeling slightly squished under the door much bigger dwarves.
With the promise of ale, the two traumatised dwarves removed themselves from the floor and onto their feet before hoisting their red haired companion to hers and linking arms with her. As she led the two shaking dwarves towards the kitchens, she couldn't help but ask;
"So, who was on top?"
The resulting wail was heard by almost every other dwarf.
They were going to need a lot of ale.