L Lawliet was not afraid to die. This was good, because the longest his best estimate gave himself to live was five years. And that was with luck, accuracy, and possibly some divine intervention. For he had just approached the point of no return... and plummeted far, far over the edge.
L Lawliet- Dies of Disease. Dies as a direct result of complications arisen from atherosclerosis.
Thus read L's own paraoxical entry in the Death Note. It could save him, and it would definitely kill him. It could carry on his career, and it would end it. It could defeat his best friend and mortal enemy, but it would allow him to continue killing for several more years, at least. It would be his first personal experiment with a Death Note, and it had the potential to be his last big mistake. And the more positive of these options could happen only if L was in a particularly serendipitous state today.
L, or, more correctly, the Kira Investigation Team, had received this particular copy of Death Note after the Yotsuba incident, and he had since been studying it thoroughly. There were two rules which particularly intrigued him: the first, that any human who writes a name must continue writing names every thirteen days; and the second, that the Death Note could only operate within a twenty-three day timeframe. He was interested in the first rule because he had strong suspicions that it was false; he was interested in the second because he believed that he may have found a loophole.
L knew that some diseases could lie dormant in the body for a long period of time before taking full effect, but the twenty-three day rule would prevent such diseases from being options with which one person could kill another. Presumably, then, one would not be able to write "dies in four years" for any death, even one by one of the aforementioned diseases. But what if one wrote in one of the said diseases, and left out the time of death? Would the twenty-three day rule take effect, or wouldn't it? L had neither the desire nor the patience to test this on anyone else, and so he had decided to use it first (and last) on himself.
But of course, what use was a gamble this large, if Light just killed him tomorrow? L had also deduced, somewhat hopefully, that a name written in the Death Note would take effect, regardless of whether or not another had entered another entry later. So, in reality, L was hinging on two non-printed rules that he had nothing more than circumstantial evidence to support.
The prospect was grim: L calculated only a 27% probability that both aspects of this plan would work. But of course, a 27% chance of survival was still better than the 0% chance he would survive if Light discovered his name without these precautions. The only other person that L had told about this was Watari.
Watari was L's mentor, adoptive father, and role model in nearly every moral aspect of his existence. L felt stronger knowing that Watari had heard him out and supported his attempts, however desperate they may be. During this same meeting, L had told Watari to delete all of the data on his personal computer should anything happen to him. L had told him it was a precaution, so that the information on Kira would not fall into the wrong hands, should no one be there to protect it. If Watari had seen that this was a signal to L's rather low expectations for the success of this plan, then he didn't show it. For better or for worse.
In short, L was risking everything for this case. If it worked, it could bring the Kira case to a close withing a few short years. And on the other, hand, if it failed, it could very well be the end of many things.
The end of an era...
The end of justice as we know it...
And the end of over 2000 years of slow, agonizing progress made while striving towards a world ruled by the people as a whole. Of a world with democracy, with fair trials, and ideally, a world of peace.
No, L Lawliet was not afraid to die. He was simply afraid to let Kira live.