Tauriel is probably the best fighter he has ever met, and he has met a good deal of great warriors.
When he was younger, Kíli used to stare in wonder at the way uncle Thorin and Dwalin swung their swords at the other tirelessly. After their training they would always pat each other's back while they laughed at their physical state; dwarves were tough, but they always managed to get a swollen eye or a bruise that took weeks to fade. Fíli and himself were not half bad, Dwalin would say when he saw them training in their mother's backyard. But Kíli needed to show off less and worry more about how to shield himself. Arrows won't miss you just because you have a pretty face, lad!, he roared from a distance, getting Fíli to laugh enough time to actually disarm him. They could laugh all they wanted, but Kíli knew that he and his brother were becoming skilled fighters, and he also knew that he had a better aim with an arrow than any dwarves he had met yet.
He could hear her blade stabbing the giant spider before he saw her. He'd been trying to get free from a single one of them, and before he could process it, there were three disgusting corpses lying around them. When he shouted for a dagger, quick, and turned around to catch whatever she might have thrown his way, he didn't really look at first. But when he turned around again in her direction, he just stared at the scene before him, forgetting for a moment that one of those monsters was coming his way. She slayed the beast with three clean cuts and with a fourth she put the animal out of its misery and killed the last spider. And she did this while calmly telling him that if he thought she'd give him a weapon, he was mistaken.
It took Kíli a few minutes to fully understand that he had been rescued by an elf from five giant spiders just to be made prisoner by that same elf, but damn, he'd never met anyone who needed less help in a fight than her.
In the elven prison, Kíli realised that she was not only a skilled fighter. She would not let his stupid attempts to make her speak faze her (it had almost hurt his self-esteem when she suggested he had nothing in his trousers) and she showed him kindness. She was a keen listener, and were it not for the bars that separated them he'd forgot he was her king's prisoner. She could laugh, and she could smile and she could tell him about the wonders that she saw in the starry skies. And she could heal a deep wound just as naturally as she put a sword through an orc's chest.
While all dwarves knew how to defend themselves (even if just throwing their strong and hard bodies against their enemies and hope to break something in the process) there was a clear division between fighters, craftsmen, healers and merchants. Everyone had their task and could excel at it, but it was rare to see dwarves who were truly gifted in more than one skill.
Tauriel could take and give life, throw a dagger and give back a treasured token. She was as strong as she was gentle and Kíli wished he were a bit more like her.
After the death of the dragon, they spend their time together. She helps him walk around Laketown, offering a gentle but firm arm to have some support.
"Your leg is getting stronger" she tells him as they stop by a half burnt house.
Kíli stares at her and doubts a second before moving his hand from her forearm to her fingers. Tauriel seems startled for a moment, but she just looks at him, with her lips slightly parted.
"I might still need your help to find my strength" he says, hoping that she doesn't laugh at him. He's a warrior, and a prince, and he's admitting his weakness to someone he's been taught to hate all his life.
Instead, Tauriel lowers her eyes for an instant before softly smiling at him.
"I'll be happy to help you, if only you let me teach you how to properly shoot your arrows" she teases him. Then she starts walking again, slowly, and Kíli feels her fingers closing tighter around his own.
