Takes place shortly before Mustang loses his eyesight; near the end of Brotherhood.
Disclaimer: I do not own Fullmetal Alchemist or any of the characters in the franchise.
...
"Damnit!" Roy Mustang slammed his fists against the desk, the wood splintering as his fists dented the surface. He gripped the edge of the desk hard enough to crack it, his teeth clenched in despair. Al sat motionless against the wall, the light in the eyeholes of the armor so dim it seemed to threaten to extinguish itself. Ed stood with his head bowed, his body motionless as he cursed himself silently. Havoc and Breda stared in shock at the phone dangling from the cord off the end of the desk, not wanting to believe what they had just heard. Feury sat quietly with Hayate, stroking his head slowly. The door swung open and Falman ran in.
"What was that noise? Is everyone okay?" he asked hurriedly, glancing around at everyone. He paused. "What's wrong?"
Mustang was silent for a moment before swallowing. "L-Lieutenant Hawkeye... was walking to Gracia's house. She left her uniform and gun here." Roy looked up slowly. "She's gone, Falman."
Falman stared at him. "What? Has she been transferred? Damnit, Roy, you can't mean what you're telling me," he demanded, his usual air of stoicism gone. Mustang just shook his head. Falman sat down defeatedly.
…
Nobody was in the office the following morning, but one particular person was not where they usually would be. Mustang kneeled on the floor, a massive array spread out on the floor around him as he connected the last circle and tossed the chalk on the floor. He glanced breifly at the materials piled neatly in the center of the array and gritted his teeth determinedly. He stood slowly, stretching out several hours of cramps as he made his way to the side of the array. He closed his eyes momentarily before opening them, a fire of resolve burning deep within. He put his hands on the ground and took a deep breath. A blue light spread from his hands across the circle, tracing the pattern exactly and flaring up in a blinding sapphire burst. Mustang turned away, keeping his hands pressed firmly against the concrete as the blinding light spiralled into the air as golden ribbons emanated from the center of the array, enveloping it completely and turning white, growing even brighter than before. Suddenly, the clear light turned red, purple running up the strands of golden light as if corrupting them. The wind grew harsher as it spun around him, and immediately, Roy Mustang knew he had made a terrible mistake.
…
Ed awoke with a start, sitting bolt upright in his bed, breathing heavily. Al jerked, spinning around and looking towards him, his concern obvious. Ed looked out the window as a faint red light lit the sky. His eyes widened. "Mustang, you idiot," he breathed.
…
Ed and Al raced through the streets, sprinting towards the warehouses with reckless abandon. As they rounded the corner, they ran straight into an utterly confused Mustang. He immediately struggled to his feet, holding up a gloved hand and turning quickly from left to right.
"Who is it? Who's there?" he demanded, his fingers pointing wildly at open air. Ed jerked backward, his hands up. "Colonel! It's me, Ed! Jesus, can't you see?" Ed snapped at him. His heart skipped a beat.
"Colonel? Look at me," he said, standing straight and looking into Mustang's panicked face. His eyes were clouded and blank, with no life in their brown depths.
"I-I… Where are you?" Mustang managed to say, still spinning in place. Ed looked at him, horrified. "Oh god, Mustang. What have you done?" he stepped forward, grabbing him and holding him in his embrace. Roy stopped struggling and let a shaky breath out, closing his blind eyes in defeat.