Disclaimer: I do not own Death Note. This is the work of a fan who has no job, and is underage anyway.
Ryuk watched the scene play out with a dampened amusement. Two forces stood waiting for the signal that would pronounce the winner. Good vs. Evil. Light vs. Nate.
The shinigami had watched Light construct his plan, and after years of living with him, began to understand the thought patterns that ruled him. Everything depended on Mikami. He would come and with Nate expecting the prosecutor to write their names on a false page they would win. Ryuk continued watching the two groups with his endless smile, inwardly cheering for his human. Light was confident, but it was well founded, and he had warned Mikami to make a false notebook long ago. He would win.
Ryuk blinked as the door opened and Mikami stepped in. The shinigami shivered and tried to focus on the numbers above the crazed man's head, staring in disbelief at them. They were far too short.
An old sense of loyalty tickled in Ryuk's chest. He wanted to warn Light that all was not as planned, but something crushed the thought almost as quickly as it formed. Almost. Ryuk fell into silent contemplation.
He remembered the first few days with Light, how strange it all seemed. The human, for that was how Ryuk had thought of Light, kept trying to convince him the world would be better with the criminals dead. Ryuk remained impassive, preferring to think of the human world as something to be used for entertainment purposes only. He had eternity to go, if he killed right, and it could get awfully boring.
The human gradually came to accept his position, and even came up with ways to buy Ryuk's talents. Light even taught him algebra. Everything had entertainment value to Ryuk, and without Light's knowing he sometimes spent the night doing Sayu's homework just for the hell of it. The girl didn't tell anyone, but after Ryuk left a note she began leaving apples as well as the harder problems out for him.
At some point Ryuk came to see the human as Light. Somehow, he began to like the boy despite his ambitions. He liked the family. He thought L looked too much like a shinigami.
Light had given up the note, and still Ryuk watched him from the shinigami realm. He told himself it was only because there was noting better to do.
Then Rem died.
Ryuk scoffed at her death, and so told Light. She was a fool to allow emotions to get in the way. Still, Ryuk continued to observe light. He was perpetually orbiting the man like a planet around the sun, with Misa as a moon. Light had that effect on people.
Gunshots snapped Ryuk out of his mental wanderings.
Light, his Light, was on the ground and bloody. Why hadn't he warned him? The large expressive eyes pleaded for help. Ryuk felt ancient emotions flex in rebellion as the man struggled. Write a name.
The small god tried to conceal the pain he felt but it was impossible. Ryuk had watched millions die; he knew what to look for. Light would be crippled for life, the shinigami noted, his hand was too badly mangled by the bullet.
Ryuk picked up his pen and easily ignored the bullets passing though his body. Foolish. They knew he could not be harmed. Black ink gathered at the tip of his pen, and Ryuk hesitated. Light wanted him to write a name.
In all the years they had spent together the brunette had asked for very little, and always offered compensation. Light had spoken to him as an equal, despite the gap in their mental abilities. Light did not fear him, as did many others. Light offered companionship to a being where all forms of affection were regarded with ridicule. In the shinigami realm love could be fatal.
Ryuk began to write, chuckling. He could not cry though the emotions raged unbridled within him. Laughter was his only means of expression. Light coughed out a few dry laughs, reading the tone in a way that only he could. Light understood though he did not want to.
"Let me see the name!"
Ryuk showed him, the look of disbelief on Lights face was heartbreaking. Light had depended on Ryuk's uncaring attitude. Light promised to show him a new world, to entertain him forever. Ryuk would have liked to taken him up on the offer.
Ryuk liked Light. He wasn't sure when it happened, but somewhere along the line Light changed from the human to his human. Ryuk stifled his laughs as Light died, showing him as much respect as he could.
Ryuk liked Light, but he wanted to live more. He wouldn't follow Rem's footsteps. Truly, writing Light's own name was the only option. Light realized it, he was sure, the second before he died. Ryuk would die if Light lived, or Light would forever live in a cell.
Ryuk took the Death Notes left, his eternal smile discrediting the guilt and sadness he felt inside. His only friend was dead.
Ryuk paused at the gate of the shinigami realm. Light had awoken something long slumbering in the ancient shinigami. Something thought long dead. As the emotions swarmed in Ryuk, he felt human. He remembered what it meant to be human.
Ryuk laughed and flew toward the building once used by L as the Kira Investigation Headquarters. His mind whirled at the new possibilities, and he realized just how deep Light's plans went.
Light knew he was mortal.
Ryuk was not.
Light wanted a new world.
Ryuk wanted entertainment.
Light knew how to get them both what they wanted, and now so too did Ryuk. Shinigami were gifted with perfect memory, and a thrill of excitement went through Ryuk as he reset the security protocols on the building and turned on dormant computers. As long as he killed every four days, the rules said he could stay.
The computers received feed from nearly every governmental database.
Ryuk slammed open his Death Note and held his pen out, truly feeling alive. At least for the next hundred years, he would have something to do. Ryuk began to write. It was only fitting that with the mortal Kira dead so should his competition be.
With Light already dead Ryuk could kill who ever he wanted without penalty.
"Light. In your memory I will remake the world."
Ryuk felt warm satisfaction flow through his body as he received the life form the SPK. They killed his light. Revenge never tasted so juicy.