Legolas and Gimli would never let one pesky generations-old racial rivalry keep them from being friendly with each other, would they? Oh, who are we kidding... they're an Elf and a Dwarf. Of course they would.
"Elves," he can hear Gimli mutter as the two grudgingly keep watch together. "Stuck-up. Proud." There is a bitterness and grudge in his gruff voice that grates on Legolas' nerves, already tout from having to spend more time with the Dwarf than absolutely necessary. This is probably the reason, he decides later, that he responds so immaturely.
Legolas laughs aloud. "Proud! Proud? And may I protest that at least I do not treat my facial hair as a treasure of my forefathers? May I remark that I do not advertise my difference from the rest of the Fellowship? Indeed, you are lucky there are not more Elves here, for with one less tolerant than I you would have been shot dead already," he points out, stroking the fletching on one of his arrows.
"It doesn't change a thing, Elf. It doesn't change a thing. I am my own Dwarf. I may be proud, but I can admit to it, unlike the perfect, oh-so-blemish-free Elves," Gimli says bitterly. "Why force me to ride with one; why make the two of us keep watch together? Would there not be more peace between us if we were kept apart," he says, regarding Legolas' willowy frame, "far apart?"
There is a rustling and Legolas has an arrow notched in a second, all irritation with the Dwarf forgotten. "Something's moving," Gimli mutters.
"I heard it!" Legolas whispers back, crouched, bow at the ready. "Don't forget that Elven senses are developed far beyond the clumsy hearing of the Dwarves."
"Don't you get me started on—,"
"Shh!"
Everything is quiet for a long time. After what seems like forever, a small, dark shape rises from the ground and pads off into the distance. It is of hobbit size, but not hobbit stature; it is crouched to the ground, timid, afraid.
As the shape recedes, Legolas hesitantly lowers his bow and slides the arrow back into his quiver. "We're being followed," he says grimly. "But not by anything of any race I know."
Gimli nods, replying gruffly, "We should wake Gandalf," but Legolas shakes his head.
"No. He has enough on his mind as it is, and the creature posed no threat. Leave him be."
Gimli looks incredulous. "Why should I take orders from you, you—you-!" He is lost for words. "You pointy-eared, Elven-faced, stuck-up, immortal pompous princeling!"
Legolas whirls around, his face far from the calm, near-emotionless screen that it had been even during their argument before. His eyes are wide and his skin pale with rage. He leans in close to Gimli, retorting, "Don't you ever call me that again, you ruffian. I've slain more orcs than you could dream; I have been defending Mirkwood longer than your entire family's pathetic life span! You want to insult an Elf? Try me. You think you're a better fighter? Let's see how you feel when you've got one of my arrows sticking out of your sensitive spot! I might laugh, I might smile, I might be young for my race, but believe me, Dwarf... I'm no 'pompous princeling'."
Gimli lays his hand on his axe, breathing loudly. "Legolas Greenleaf, I hope you're ready to die," he grumbles, heaving Legolas away from him.
"Likewise, Gimli, Dwarf," Legolas says icily, notching an arrow and pointing it straight at Gimli's heart.
Legolas is about to shoot when he hears something soft, subtle. A cracking twig, a bending blade of grass. He turns away from Gimli (who can't believe it), and peers into the darkness. With his Elven-sight, it is not hard to see Gandalf standing behind where he and Gimli were about to kill each other.
"Gandalf," Legolas breathes, relieved that the noise he heard wasn't something more malevolent. "I didn't know you were awake, I would have..." he leaves the sentence hanging, not quite sure what to say. Awkwardly, he lowers his bow.
Gimli cries out, "Gandalf?" and immediately Legolas and Gandalf both answer with loud 'shush' noises. Offended, Gimli quiets down.
"Legolas and Gimli, you were so loud an orc could have heard you from a league away!" Gandalf scolds, his face grim. Legolas hangs his head, somewhat ashamed. He feels like a hypocrite; normally he is the one telling other people that they are too loud. "If you can't get along for just one night, then one of you will be sent back to Rivendell and replaced by somebody a bit more civil. Now go to sleep, both of you, I'll finish the watch."
Legolas and Gimli nod and trudge away to their beds, humiliated. Legolas is almost sure that Gimli is asleep when he hears a crudely and loudly whispered statement echo through the darkness: "I still don't like you, Elf. But I'm willing to peacefully ignore you if you'll do the same for me."
Legolas smiles in spite of himself. "Agreed."