Tony Stark held the burned arc reactor in his palm and knew it wasn't enough. Blue light flickered in his chest, the small reactor that kept him alive. He wanted more. He wanted one big enough to end the world's need for oil. But the prototype in his hand was already dead, its core cracked from the last test. He had built it in this tower and it had failed in eleven seconds. The atrium stretched above him, all glass and white stone, quiet as a church. Sunlight poured through the tall windows. He walked past the potted trees to the workbench he'd dragged into the middle of the room. Screens glowed around it. Numbers scrolled too fast to read. He pulled the fresh core from his suit's chest plate. The Mark 3 stood behind him, headless, an empty red-and-gold shell on a stand. He'd taken the helmet off hours ago. He worked better with his own eyes. "One more," he said to no one. He slid the new core into the prototype and locked the housing. His hands were steady. They always were, right up until they weren't. He stepped back and fed it power. The light climbed. Yellow, then white. The screens spiked. For three seconds the number he wanted sat right there, bright and real. Clean energy, more than any city could burn. His breath caught. He had done it. Then the housing screamed. The core flared and blew. Glass cracked across the nearest window. The blast threw Tony back onto the polished floor. Heat washed over his face. Alarms howled through the atrium. He lay there, ears ringing, staring at the ruined bench. Smoke curled toward the dome. The prototype was slag. But the reactor in his own chest stuttered. Tony sat up fast. He pressed his hand to it. The blue glow dimmed, surged, dimmed again. The blast had spiked his own core. The one thing keeping shrapnel out of his heart now skipped like a bad engine. He dragged himself to the bench and pulled up the readings. His hands were not steady now. The chest reactor showed a fracture line, thin as a hair, running through the housing. Days. Maybe less, before it failed for good. He thought of the man who had asked him last month if he ever considered walking away. Tony had laughed then. He wasn't laughing now. Someone had wanted his tech to turn on him. He was sure of it. But tonight the enemy was his own design, and it was inside him. He wiped soot from the screen and started a new file. The world reactor could wait. First he had to keep his heart beating long enough to build it. He reached for a fresh core and got back to work.