Disclaimer: I don't own the rights to Death Note. This is fan fiction. Get it?
Warning: This might offend some people. Read at own risk.
Edit A/N: Attention all nitpicky people who say that this story is AU because durung the handcuff arc, Light had no memories of the notebook. There is one, in numbers 1 day where he has his memories/personality/etc as Kira but is still handcuffed to L. Chapter 53, page 13 he regains his memories. Handcuffs still in place. Chapter 55, page 19 is the last time we see them handcuffed together(evening). Next day (It also reads next day in the manga) the handcuffs have been removed. So, this evening is precisely where my story is taking place.
In the oppressive silence of the large, dark building the hum of the computers and the sounds that L made eating were the only things to be heard. The coffee-table before him, the floor below him and pretty much every flat surface within arm's reach of the pale detective was littered with crumbs and wrapping papers. Crouching on a functional white couch, he was currently shoving truffle after truffle in his mouth, accompanied by crunching, slurping and the occasional delighted "mmmh".
Normally, Light would have scraped up his tolerance and simply ignored the gluttony taking place right next to him, but not at 3 o'clock in the night as it was. After staring at the pale glow of the screen for hours on end, and only after even L's seemingly unblinking eyes had started to go raw, the peculiar genius had decided that it was the perfect time for a snack. Bound to him by the thin, glittering length of chain, Light had no choice but to sit next to L on the comfortable, if food-stained, couch and give him a disapproving glance every once in a while. And even though the display of mindless hedonism annoyed him to no end, it was, in a way, relaxing to play make-belief a bit and pretend they really were friends. No real affection, but the opportunity to talk to someone matching his intellect. This was made more special and more important by the fact that Light knew it was of limited time. Tick-tock, Ryuzaki, your time is running out.
L shoved another forkful of cake in his mouth and licked his fingers, which were smeared with icing, in a show of the thoughtless sensuality he always displayed when eating. He leaned forward a bit in his strange, compact way and seemed to be pondering over a cup of coffee that was really more creamer and sugar and almond flavouring than anything else.
"You know, Light-kun, if anybody decided to poison me with prussic acid, the chances would be high I wouldn't notice it. The almond flavouring in this coffee is so strong, it would be easy to sneak some in."
"Hm? What are you talking about, Ryuzaki? Who would want to kill you with poison, of all things?"
"Well, if Light-kun was Kira, it would be easy for him to manipulate somebody into poisoning my drink. Perhaps he would even decide to kill me in a way different from his usual methods, so he wouldn't be initially suspected. I do have other enemies, you know."
Without hesitation, Light reached for the cup of coffee and took several deep gulps, wrinkling his face at the too-sweet taste. He looked L in the eye.
"Now there are several different scenarios. Either this has been poisoned by Kira or someone else, in which case I would be dead in a few minutes. If that was the case, and Kira was the perpetrator, the chances would be high that I would be innocent. Or the coffee is perfectly harmless, and no definite statement can be made about my innocence or guilt."
"So either you would be dead and probably innocent, or alive and not cleared of the suspicions against your person. Even if you were Kira, though, you couldn't know if this coffee was poisoned by anybody. So what you just did was a very foolish and reckless thing to do, just to prove your innocence. The chances of you being Kira rise another five percent."
For a few minutes, there was complete silence. Then L took a big bite of a doughnut, washed it down with a mouthful of coffee and calmly said; "Now that this poison business is out of the way, I can enjoy my snack again. Thank you for tasting the coffee for me, Light-kun. Do you want a lollipop?"
"No, thank you. I am not particularly hungry."
L crammed several strings of black liquorice in his mouth and regarded Light with his equally black eyes. Finally, he chewed, swallowed, and said; "Would you mind standing up? I have to use the bathroom."
Silently, they went to the bathroom and L arranged the long chain so it ran beneath the door, which he then shut and locked. Over the still slightly eerie drone of the computers, Light heard a soft "ffumph" sound, the clatter of the toilet seat, and then a series of coughing and retching noises. The toilet flushed, the water ran, and the chain jangled against the floor. Finally, the door opened and L emerged, his pale face sweaty and white as the walls. He was wiping his mouth with the back of his hand. Light regarded his adversary's skinny figure with something quite close to horror.
"Daijobou-ka, Light-kun. Don't worry, it's allright."
A/N: No, I don't think L is bulemic. I just had the idea and I had to write it. Hope I didn't offend either bulemics or L fans.