Light character study, edited for punctuation, minor stylistic elements, and changed Raito to Light. Sort of a companion to Invisible Parallels, but they're not really connected. This one is also based much more guesswork. Most of what I made into L in Invisible Parallels came from the manga, with only a little of my own experience to connect facts logically. This has much more of my thoughts in it, and virtually no support from the manga that couldn't be interpreted a thousand other ways just as easily. So while I'm fairly certain that Invisible Parallels sets up something pretty close to L's actual personality and motivation, this is more like one potential personality and motivation set for Light. Entirely plausible, but no more than an infinite number of others. Enjoy.
Light knows, perfectly well, what he's doing. He knows that when Ryuk tells him that those who are followed by a shinigami suffer misfortune, he isn't an exception. He may delay the moment when he is broken utterly, but he can't prevent it. The only way to prevent it would be to give up—either confess, or forfeit the Death Note finally, making sure that he'll never get it back.
With that in mind, Light knows he'll never do anything like give up.
A genius never gives up.
Light has often thought that the world treated geniuses much like sacrifices. Ever since he'd been named a genius, almost everyone revered him, but almost no one cared. He was expected to be perfect, the best at everything—and he was, even if he had to throw himself away to do it. He realized, sometime just after starting high school, that he wasn't normal. He was so strange, he had to wonder if he was even human anymore.
But that was what he had to be in order to be perfect, and more than anything else, Light Yagami will never allow himself to be imperfect. It's not the imperfection itself that bothers him, so much as the disappointment he would feel from others. If anyone else messes up, even completely fails, at the tasks Light is given, it's to be expected. They were normal. It's amazing that they could even try to accomplish it. But if Light fails, even if it's only by being a little slow to finish, or being misled partway through before he corrects himself—that's his fault, because he's a genius. If anyone else fails, they're normal, and commended for trying. If Light fails, he's a genius, and a broken one, appreciated as much as a broken toy.
So he lets himself break a different way. He learns, first to control his emotions, then to hide them, then to eliminate them altogether, all the while acting the proper ones out perfectly, and finally learns, also, to create his own emotions. He controls his own mind as easily as he might control the actions of a puppet or a character. Easier, he thinks, remembering a classmate who talked about writing, how the characters would come to life and do things they weren't supposed to do. Light's own mind is clay, for him to mold as he pleases—and that is always, always, however he thinks people expect.
A mirror, a sponge, a detective, reading what others expect of him, absorbing and becoming it, because he never knew to do anything else until too late.
There are occasions, when the clay does something he doesn't expect, or slips back into something else—whatever it was before he gained such control. Once in a while, when he encounters an event that he has no idea how to deal with, like finding the Death Note, or when he thinks he should react strongly, like when L died. Then his mind gets out of his control a little, slides back to the first or second step, when he could restrain his thoughts and emotions, but not destroy them.
Light lives for those moments. They may be a crack in his perfection, but they are only slight, hairline fractures, that he can hide or explain away. And even if those fractures are just the beginning, the first signs of Light's impending doom, the beginning of the end in which he will break entirely—well, only Light knows that. The others only see it as more depth to his personality, another layer of hidden glory.
It is glory, Light thinks. There's a glory in death and blood and the end, too. It's just not the glory they expect.
So Light tolerates Misa, even though he could kill her, now that Rem is gone. She helps his image of perfection—it would be rude to turn her away, and such a perfect person as Light surely deserves the best wife, like a model. And she is his weakness—the flaw in his plans that, he thinks, will let Near or Mello catch him, someday. But that doesn't happen; Misa is much smarter than Light first thought.
Light wishes, sometimes, that Misa was a little more stupid.
And Light continues his dangerous game, even though he knows that it will be his end. He defeated L, but now he must fight Mello and Near, who learn from their predecessor's mistakes, and if he kills them, he is sure that someone else will come to take their place. The game will continue, on and on, until Light—and Kira—is dead. He could just let go—all he would need to do would be to forfeit the Death Note, and he would be free, alive, with a model for a girlfriend and a job others would kill to have. He could have a perfect life—if he were just willing to give up, or take a step back.
A genius never steps back.
And so he continues, always walking forward, never looking back, never caring who he loses along the way. He never runs—it would be undignified, and Light really doesn't want to break, when he thinks about it—but he never, never stops. Even if no one knew, even if it would make him seem better in human eyes, Light knows that, in his own mind, it would destroy him. He knows he is wrong, now, he is entirely willing to admit it—but still, he can never stop.
Light laughs sometimes, when no one is around. He isn't even sure why normally—because he's so pathetic, destroying himself like this, or because the others are such fools, worshipping the lies he gives them, or because the sheer irony is just too great to miss, in this perfect disaster he's become. All he knows is that he laughs—hysterical, desperate, despairing, and feeling more alive than he ever is at other times, because as terrible and pathetic and everything else as that laughter is, at least it is real.
Light wonders sometimes if this is insanity. He knows his fate, knows what caused it, every event and detail and thought from when he was born that led him to this point, and he knows any number of ways that he could save himself. And he refuses to. It is a logic that, on some level, even he does not understand—he only knows that what he would destroy within himself if he gave up—whatever it is—would hurt him far more than however he will shatter in the end.
A genius, a sacrifice, a synonym.
So Light Yagami keeps walking, always forward, a willing sacrifice to himself, a god entirely able, yet still incapable, of granting himself salvation from himself.
It is no wonder, Light thinks, that Ryuk finds him amusing. He does, too.