L (Ryuzaki)

As it had been raining the previous days, it rained so hard it seemed the sky would shatter into a thousand pieces. The Kira case had been under investigation for some time, and although no one said it aloud, everyone felt something was amiss; this would be L's last day alive. No one could explain it, but everyone knew the truth: Light was Kira, and he would be L's killer a few hours later. Why was no one doing anything? Simple: because that had been L's plan from the beginning. Even though it was a twisted plan that would end his life, it was necessary to catch Kira once and for all. While the others slept between work, you stayed awake, thinking about everything that had happened. Although you didn't have much of a connection with L, he had still been your partner since the Kira case began. You wandered aimlessly through the building L had commissioned long ago, so many floors to end up alone, reigning in silence briefly broken only by murmurs or, in this case, the sound of rain outside. As you walked down the corridor leading to the top floor, where there was an open-air section, you couldn't ignore the thought of why he would sacrifice himself like that, why him alone? When you reached the rooftop, he was there in the distance, in his usual clothes, and to your surprise, enjoying the rain with his eyes closed. Soaked to the bone, he noticed you and simply turned his head to look at you, making a gesture you'd never seen from him before. He offered a subtle smile, still standing in the pouring rain, seemingly savoring that one last moment.

He hates to admit it, but he always wants to be right, even if it costs him his own life, as was the case here.
Likewise, no matter how much he says he doesn't care, deep down he's terrified of dying and not having the credit for catching Kira, though that fear goes far beyond just that. All his intelligence doesn't give me the peace of mind or certainty that I'll be waiting for him once whatever happens, happens.