1. The birds
Kakashi hates rocks.
He hates them with passion and when he's all by himself he uses any convenient technique he copied to smash as many large rocks or boulders as he can. Afterwards he slumps to the ground, feeling a bit more empty and a bit more exhausted then usual and allows his lungs to bring out a tired sigh.
For him - Obito is dead, dead, dead - that makes him laugh, but the truth is (and everyone who knows him, knows this too) that he rarely laughs, and even when he does the mask he so carefully carries on his face hides it.
2. The light
Kakashi hates white paper. Anything white, in fact, be it papers, cloth's, or pottery. He hates it with vengeance and tends to destroy everything completely white (pure and clean) with any given chance. Papers burn, easily - and he likes the fire and the colors, even though he doesn't feel the warmth, cloth's are either ripped apart or burned too - and by doing that he's only venting out, and pottery is good to use when he needs to smack one of his students or just pretend he's sleepy when it slips through his fingers.
White is the color - of Rin who is gone or dead, gone or dead, and most possibly dead - that makes him frown and something dark, too dark and too heavy and troubling tugs at his heart. His face often wears a painful expression when he thinks of her, but the mask hides that too.
3. The speed
Mask is a precious thing for him to have. Before he used to think that he's even more mysterious with it, that it ups his reputation as the 'Cool Guy', and when he finds out that isn't it he transfers the reasoning to hiding his face to simple - just because. And that works marvelously because Kakashi is a person that likes to hide, specially in shadows, although he has no blood relations to the Nara Clan.
The speed - he's alive, alive, alive and it kills him to think about it - is him, Hatake Kakashi, in so many ways (that kills him even more). He's the only one still here, alone, left behind like a weak puppy in a strong litter. He hates that with more passion then he hates some particular people because no matter how hard he tries the mask cannot hide the fact he's the one who lived.
4. Chidori
In one long night of thinking, Kakashi decides it's not good to dwell on dreams of what if, and why not. It strikes him as odd to see it just now, when he thought about it for far too long to count, but it takes him all of five hours to train himself to master the Chidori.
He takes the rocks and their breaking splinters (Obito is stored in his muscles); he takes the light and it's dazzling beauty (Rin is always in his blood); he takes the speed, because that's the only thing he can give that's left (he, himself is who he is) and combines it all to make the only technique that is his and his alone.
That night he also realizes that the mask stays on, so that no-one would see him for who he really is. Not a ninja who kills to live, not a teacher who teaches others how to kill (and live too, but that's not the point here, is it?), not a sparing partner that can't really beat his life-long rival, not anyone in special. Just a man with too many broken dreams, and hopes and with too many dead people he loved.
Most certainly not a genius at all, he muses, and the Chidori sparks to life for the first time.