AN: I was listening to Coldplay's The Scientist when I came up with the idea for this tricky little one-shot. It left me thinking...

A tremor of silence filled Billy's ears as he stood motionless, holding this – this costume in his hands.

Red clothing snapped onto white skin, and white hands were thrust into black gloves.

This wasn't what she'd wanted; this wasn't what he wanted-

Slowly, almost mechanically, he stepped forward, feet squeaking in his dreadful new boots-

Oh god, she was gone, she was really gone. What would she think if she saw what he'd become?

Dr. Horrible spread his fingers and pushed open the doors to the cold stares of the ELE, grinning eagerly as he entered his first League meeting. This was the doorway to power; now he had everything…

He gulped and pulled down his goggles so they wouldn't see the desperation in his eyes. 'Keep your head up, Billy buddy…'

Four months passed – four months filled with nothing but fear, dominance, and maniacal laughter. Legions passed from behind Dr. Horrible's commanding arm as he stood over the destruction of what had once been his own society. Explosions rocked the city sky, and heist after heist left it a shattered ghost of the past. Under his arm, the ELE had ruled until there was no more left to rule. Bil-Dr. Horrible had once been skittish about the impulse to commit "classless" crimes, but Penny's death had brought a new chill to the surface of his personality. It certainly was a brand new day-

Penny.

Dr. Horrible paused mid-laugh. He hadn't heard that voice inside his head for months. He came out of his daze and stared blankly down at the government building he was about to destroy. What was this, the city hall or something? He couldn't remember – not that it mattered anyways. With the public disappearance of Captain Hammer, work had become very easy for the ELE. But the building brought some type of nagging memory to the surface of his exceptional brain. Oh right, that stupid freeze ray – and

Penny.

He remembered it now. He remembered her. The memory had never left him…he'd just chosen to stash it away for all this time. It would hurt less and give him more time to focus – focus on what? Oh right, city hall. He raised his gloved hand – it was getting worn now, but he'd just buy new gloves – and looked emotionlessly at the small device clutched in it. His Heat Ray had replaced forgotten dreams of the Freeze Ray; one press of that button, and the building would be gone forever. No more memories. Bye bye.

Penny.

Dr. Horrible stood firmly, tears building up behind his eyes. He shook his wrist in the air, and a crowd below him cheered with enthusiasm. The fan clubs had long since changed their allegiances, and he found himself more popular than Billy could have ever dreamed. Billy. He hadn't used that name in a while. His hand shook again, not with force but because he was trembling. Dr. Horrible looked down from the tall building he was standing on, and fought to keep the tears from escaping onto his face. It took more effort than he realized – more effort than he'd put into any project in months – and he couldn't hold it in. One tear made its way onto his skin, but he pressed the button before anyone below noticed. It evaporated as he was instantly blasted by heat.

He walked blindly through the rest of that day, accepting congratulations and continuing his rampage through the remains of the city. No mercy was shown to any resistance; no more tears were allowed to escape from his eyes. Bursts of flame and debris were no unusual sight to Dr. Horrible, and he created them as he was instructed to do so. It was funny – he had envisioned himself as the leader of a new world, a new society, not merely Bad Horse's pawn. He would have quit long ago, but he'd have been tracked down and killed for the information he knew…and the power was too addicting. He couldn't just run from it; he had a thirst for it that overpowered everything, and that was his weakness.

Dr. Horrible opened the door to his old apartment and fumbled with his rusted ring of keys. He suddenly glanced up to see his old lab bench exactly how he'd left it; without a sound, he closed the door behind him and sank down against it. The doctor hadn't set foot in this place in weeks, not since he'd set up his new laboratory at the sleek, modern ELE headquarters. He put his hands on his face, and the black rubber smell enveloped him at once; he tore the gloves off in a rage and hurled them across the room. Spasms rocked him as he curled up against the door and frantically breathed in the familiar air; it didn't help to calm him. Billy finally let go of the walls against everything he had once been and took on the full reality of his fate. He looked upwards in desperation and sobbed pitifully – he missed her. He missed talking to her every day and seeing her face through the Laundromat window. He missed video blogs. He missed frozen yogurt. He missed courier vans – and as he gazed sadly up at the ceiling, Dr. Horrible felt utterly broken.

He didn't know how long he had been slumped against the door, silently weeping into his own knees, when a breath of cold startled him. Billy rose his gaze. No – that was impossible – Penny, yes, Penny, stood no more than 3 feet from him, as beautiful and calm as ever. He scrambled onto his knees and tentatively stretched out his hand – she looked real. She gave him a sympathetic smile, visible tears beginning to well up in the corners of her eyes.

"No—don't cry, I'm sorry…I'm sorry…" Billy squeezed his eyes shut in pain. "I'm sorry…I didn't mean to hurt you." He opened them and she was gone. His heart wrenched in desperation. "Don't leave…"

A twinkle to his left led Billy's eyes to the area by his lab bench, where Penny stood in the dress she had worn…it was beautiful. He wished she had worn it for him that day – he froze as he remembered the chill of seeing her lifeless eyes leave him for the last time. Billy didn't want to come any closer, but Penny raised her hand and beckoned him to her. He didn't hesitate to oblige, and as the final step closed the distance between them he launched himself into a hug. The feel of her fingers on his back was real, and her chin resting on top of his shoulder was real. She was really here. He could protect her now. Billy pulled her closer to him and breathed in relief. Penny moved her hand up and down his back in comfort, but he had already received all the comfort he needed. He drew back slightly and took her hand.

Glistening snowflakes began to fall from the ceiling of Billy's apartment as he and his lost Penny twirled their way around the lab bench, dipping and waltzing to some forgotten tune. The ground turned to snow and Billy could almost begin to see his breath, if he had any left. He smiled for the first time in months. There was so much to learn, so much to tell her…their heads touched and she smiled back. He and Penny were connected now, as if they shared every thought. There was no need for either to speak.

Billy opened his eyes. He was on the floor next to the lab bench, desperately clinging to the air to draw Penny back, but she left no traces. He had to find her. It wouldn't be easy, but he knew he would find her. Though the dream-snow had gone, the twinkle in the doctor's eye had returned and the rusted gears of his independent brain clanked with life once more.

Billy dug through an old closet, throwing aside dusty hangers and sheets until he found what he was looking for. A lonely dry-cleaning bag hung at the very end of the clothes rack, awaiting his return. Billy carefully unzipped the bag, his mouth curling into a grin. A few minutes later, the red jacket lay in a heap on the floor next to the carelessly thrown black gloves and boots. The doctor's white coat was back where it belonged. He affectionately slid his fingers into his old white gloves; they smelled like home and old sweatshirts. The goggles didn't need replacing. Billy had never desired a better pair. He made his way back to the lab bench, clearing it with a sweep of his arm. He didn't need any of that junk anymore; he had a new project to work on. Billy unearthed old tools and mechanical parts, reminding himself of the days when he always had some idea to build on and some invention to fiddle with. Sure, it had been marked with failure; but it was what led him to success, wasn't it? What was so bad about being the underdog? It had only made it more impressive when he won. Billy wanted that back – he wished, desperately now, that he hadn't built that death ray. If only… he shook his head and reached for another tool, distracting himself with his work. Failure was part of the experiment.

It was time to start over.

Now, Billy had it, a physical product to show for all of his work. It was nowhere close to completion, but it was something to look at. He had finally begun to piece everything together; he knew what he wanted to do. Balancing himself on a chair, he stretched his arm up to blast the top of the metal with his high-power torch. He would have used the Heat Ray, but it wouldn't do any good here; it was only useful for destruction. Billy realized just how much his experiments had changed…how much he had changed…and how dangerously close he had come to losing this life forever.

Penny, elusive as always, managed to creep back into the doctor's thoughts. He hadn't only changed her life for the worse…he had taken it, and Captain Hammer only chose to abandon the prize that had once been his. Captain Hammer had probably never even cared about Penny. He was just a big…joke. A dork. A failure. Everything that Billy had pictured himself to be. And this invention…well, if it succeeded, maybe he could change that. Maybe Penny wouldn't have to be alone. Whether it would bring him to her or bring her to him, he knew it would reunite them somehow. That was the greatest thing about his inventions; he never knew how they would end up working, but they always achieved their purpose. If Dr. Horrible's invention had made this mess –maybe Billy's could fix it.

Lost in his memories, Billy let his hand slip and the torch was pressed too close to the flaming metal. His eyes widened in realization and he averted the blast to prevent it from damaging his work; sparks flew in every direction, bouncing off the lens of Billy's goggles and temporarily blinding him. One sent a pinch of searing heat onto his neck; he flinched and opened his eyes to meet Penny's cool gaze. The sensation on his neck was no longer pain but relief as her fingers, slightly cold, rested where the spark had injured him. He descended from the chair and walked carefully, leading Penny out of the apartment and outside. Endless green fields replaced the ruined city, stretching infinitely to a horizon of freedom. Billy turned back to Penny's brown eyes and smiled. His teeth met the air for the first time in…whoa. When was the last time he had been this happy? They resumed their dance, spinning in the open air and sharing absolute bliss. Billy was laughing – not his evil laugh, the one he had worked years to perfect – this laugh came from somewhere else, somewhere he hadn't bothered to look in a long time. Penny brought out a different side of him: not Billy, not Dr. Horrible, not even that third persona who killed mercilessly and lost all sense of justice. Penny was his fourth identity, and if he succeeded now, he would take hold of a future that he had long since been deprived of. Oh, the life they could have had together – what they still could have together –

Weeks went by, and Billy wasted no time in polishing and perfecting his machine. This invention was different – this one was more important than all the others combined. No one had said this project would be simple. It needed to be absolutely flawless before its trial…he couldn't handle another failure. Not after the death ray.

He worked late into the night; he couldn't remember what day it was, or what month it was. Billy's hands kept moving and his mind kept whirring until his body forced him to relax. The moon rose above the desolate city skyline, illuminating shattered windows, crumbled statues, and one small scientist who had curled up in his enormous armchair beside the invention that had become his life. As he rested in the spot where he had planned his future with Penny; he twitched and grinned in his sleep. Who said that future was still impossible?

Morning found Billy hard at work once more – suddenly, he was left with a completed invention and a plug that was one outlet away from revealing his future.

"No, no, the time isn't right…" he muttered, fearing for the worst. His breaking point was failure…and if this invention failed, he had no more reason to live. Billy wasn't sure, nor did he care, if the ELE knew where he was. Was there even an ELE anymore, or had his absence left them in ruins? They certainly hadn't come looking for their lost member…not that it mattered.

Billy spent days contemplating whether or not to plug in his creation. Every time he decided to act, he ended up pulling away and simply gazing at it in wonder. For once in his life, Dr. Horrible was happy; he had completed something, and success was in his grasp. He was clinging to a never-ending hope of achievement, afraid of further failure and content with what he'd accomplished. He had truly reverted back to his old ways. Exhausted, he slumped onto the side of the machine and napped soundly against it. He still smiled in his sleep.

The sun began its descent downwards for what seemed like the millionth time, and Billy once again found himself deep in a staring contest with the plug. As always, he just couldn't get himself to – move – his gloved hand slowly reached for the wire and grasped it. He breathed more quickly; this was new. He stared at his other hand, willing it to have enough strength to grab the other wire – it did. Billy held the two parts, suspended in midair, present in their ready position. Penny was waiting for him. He relived the scrap of metal from his death ray piercing her side; he relived the desperate look in her eyes as she recognized him for his true identity. He relived the pain of losing her forever. But maybe forever wasn't…forever. Billy focused his gaze and brought the two wires together.

A rush of warmth enveloped him; this one was different from the blast that had dried his tear on that building so long ago. This wasn't the jolt of pain from the spark of his mistake. The young man breathed in and smiled as a familiar breeze rustled his hair. He opened his eyes.

"Penny?"