A/N: Written out of a random bout of inspiration. Not my best work, not my worst.
The gleam in his eye and the grin on his face. Two usual signs that he was up to something. But this time, it was something more.
This was it! This was the moment he'd been waiting for. Eight years is a long time to wait, but it would be worth it, he was sure. Eight years is plenty of time for something to build. Hatred had bubbled in his blood for long enough, and now it was time to come spilling out.
It wasn't his blood that stained the floor, however. His entire body shook as he absorbed the terrified look of his enemy's face. The fear and suffering in his eyes made Robotnik want to scream with triumph.
He was doing it! He was defeating Sonic, so easily, and it was so good!
He'd wasted years chasing him round and round and round. The rage had built as Sonic circled him endlessly, taunted him, destroyed his machines, made up name after stupid name for him...
"How does it feel, hedgehog?" he questioned quietly, allowing Sonic to feel the cold of the metal against his wounded leg once more. "Is it worth it? All those years of never quite defeating me? Are you happy about all those times you let me go?"
Sonic struggled and gasped. The stone floor was cool and damp. He lay in a pool of his own blood. He ached to scream but knew it was useless. He tried to avoid Robotnik's shielded eyes and diverted his own to the floor as the Doctor went on.
"I helped you, do you remember? I helped you to save the world time after time. Want to know why?"
To think... All those years, all those robots. What a waste! He'd wasted his genius for so long, certain that each machine was better than the last, absolutely sure that this one would slow Sonic down, capture him, kill him.
But no! All it took in the end was the simplest of tools.
Doctor Robotnik pressed the flat side of the knife to Sonic's chest and held it there, blade pointed away from the hedgehog's throat. For now.
A knife! Just a simple, ordinary knife. Wait until he was still, wound his leg so he couldn't get away. So simple, so brilliant! Yes, he was brilliant. He'd always thought so. Why had he not done this sooner, saved his materials and his genius for after he'd conquered the world? He should have felt stupid, but he didn't. He felt amazing.
"I did it.. because I knew this day would come. I knew it!"
The blunt edge of the knife nudged Sonic's throat, and he panicked.
"You're crazy!" he managed to yell, tears streaking his face. Tears of pain, frustration, helplessness. He thought of his friends.
Robotnik grabbed the blue hedgehog's face and turned it sharply to look at his own.
"You're probably right," he beamed, shoulders shuddering with suppressed, mad laughter. "But it doesn't make a difference."
The knife flipped in his hand suddenly, and he thrust his arm forwards. Sonic choked, and fell limp in "Eggman"'s arms.
"I still win."