Fíli grew up surrounded by dwarf wisdom. It had never been explained to him, but since he was a bright child, it soon made perfect sense: it was safe enough to go straight where you wanted to when you were underground, but there was no way of knowing what dangers lurked above ground.
The only way to travel safely with the threatening nothingness of the sky above you was to loop back, zigzag across even terrain and pass certain landmarks from at least three different directions. After all, you needed to throw possible enemies off your trail.
He had seen it work countless times. On one memorable occasion, a pack of orcs chasing them had watched in bewilderment as Dwalin led them in a dizzying pattern across a large forest clearing. After an hour, the orcs had simply shaken their heads and turned away in what Fíli could only assume to be frustration.
…
Fíli could only despair at how unskilled Men were. The first time they had briefly joined a group of them during their travels, he had been terrified. The Men had simply kept to one path, travelling straight ahead without any detours through brambles, thickets or bogs. Fíli had been horrified that his uncle said nothing against this folly.
However, by the time Kíli asked him quietly why their uncle wasn't insisting on a curving and looping route, he had worked out the answer.
…
"Uncle Thorin would be foolish to give away the knowledge of our ancestors. Getting lost is a skill only dwarves and perhaps very few Men possess. There is even the danger that if they find out how skilled and stealthy the line of Durin is, they might capture us and keep us as slaves so that we can lead them. I even heard Uncle Thorin mutter that they must never know about us getting lost."
Kíli's eyes widened and he nodded.
…
When they finally settled in the Ered Luin, Fíli really began practicing getting lost. He soon knew exactly 297 ways to get from the small dwarf dwelling carved shallowly into the mountains to the closest human settlement. His longest path took five hours, while the average dwarf needed three and he had seen careless humans walk the distance at a leisurely pace in barely an hour.
His uncle, however, was so skilled that Fíli was regularly in awe. When Thorin wanted to go to the human town, he left before sunrise and only barely made it to the human inn before it closed at midnight. His record when accompanying a transport of ale had been three days.
Driven by the need not to disappoint Thorin, Fíli regularly went into the wild, blindfolded himself and set off into a random direction, spinning around until he was dizzy at regular intervals and then setting off again in a different direction. After a while, Fíli took off his blindfold and let himself discover new paths to add to the network of paths carefully mapped out in his head that he would use to get lost.
To his great disappointment, Fíli always soon knew which way he had to turn in order to go home. He was sure that if the sun, the moss on the tree trunks and his familiar landmarks didn't keep distracting him and setting his feet on familiar paths, he would know so many more paths to choose from when getting lost.
…
It was shortly after they entered Erebor that Fíli first experienced the confusing feeling of being completely unable to get lost. He and Kíli had been sent to carry back some more of their packs from Smaug's lair to the front gate where they were currently camping.
Kíli had wanted to leave the main hallway to inspect some of the marvelous stonework and after a few minutes of wandering from pillar to pillar and inspecting the details on doorknobs and rafters, Fíli and Kíli suddenly realized that they had no idea where they were. They tried reconstructing their way by remembering which structures they had looked at, but after a few turns, they came upon completely unfamiliar spike-like carvings in the stone.
Again, they tried to retrace their steps. This time, they seemed to go in a circle and returned to the spike-like carvings.
Kíli looked at Fíli. "What do we do now?"
Fíli looked around and shrugged his shoulders. "There's no sun, no stars and no moss here to tell which direction is which. The only light is that of our torches and Smaug left no soot this deep into the tunnels, so we can't use that. In a human home, I'd use the dust in which we could see our footprints, but you know as well as I do that dwarven stonework doesn't allow dust to gather. I guess there's nothing for us to do but keep trying."
…
Several hours and countless wrong turns later, they heard Thorin's voice echoing down the tunnels and shortly after they replied, their frantic-looking uncle came around a corner, followed by Balin.
"What happened? Are there goblins?"
"No, no goblins or orcs…"
"Then why are you here, two levels below the front gate and the throne room?"
Fíli and Kíli looked at each other sheepishly. "We looked at some carvings and then we didn't know where we were any longer…"
"Are you saying you got lost? Here in the mountain?!"
"No, we definitely aren't lost! The problem is that nothing is familiar and there's nothing we can use for orientation…"
Thorin looked dumbstruck. "But this is Erebor! It is underground, any dwarf can find the right paths underground…"
He trailed off when Balin cautiously placed a hand on his shoulder.
"Thorin… they were born above ground. I think it's possible the lads don't have ore sense. Maybe they are as hopeless below ground as we are beneath the open sky."
The three of them stared at Balin open-mouthed.
"Sorry lads. To be on the safe side, you two probably shouldn't go wandering around without one of the older dwarves, just so you don't get lost again."
Fíli stared at him disbelievingly. "But I told you. I can't get lost here. There's not a network of paths in my mind I can choose from, there's not even a single boring route I can take as Men do. There's just a bewildering mess of tunnels that mostly look just the same. I'm telling you, I can't get the least bit lost in here!"
Balin shook his head sadly. "Lad, I don't think that word means what you think it does."