Extreme liberties have been taken with the backstory here. I apologize for any ruining I might have done, but I am no expert on Batman. Please review and tell me what you think about this rapid plot bunny and also if I got the rating right. :)

You want to know how I got these scars?

It had been an ingenious device really thinking back, when the years were as blurry as could be but the pain was still sharp and strong.
"If you stop smiling then both of your precious little friends will die!" the croaky voice had hissed into his ear, clouding his senses with the scent cheap tobacco and even cheaper alcohol, "And this device will tell me when!"

My father was a drinker and a fiend.

Well that part would have been right, if it truly had been his creator who had first strapped the sensors to his face after forcing him to smile a gross mockery of his smile. Number One was a genius, evil, but a genius. No-one could deny that. But his atrocities were focused on Otto himself while everyone else was collateral damage. That man had been focused on his ex-wife while Otto and everyone else had been the collateral this time. It had been a nice change, he mused, swallowing the liquid in his glass all at the same time.

One night he goes a bit crazier than usual.

The madness that he saw in that man's eyes had scared Otto. It had used to scare him that he saw the same madness in his own eyes especially after the accident, but not anymore. Now he embraced his madness for it had brought him to a new understanding.

Mommy gets the kitchen knife to defend herself,

A single sliver of metal, stolen from the metal works where Wing had been forced to work was the weapon of choice. He never did like guns even when he was forced to use them. The shard of metal left a deep wound on Otto's captor as he was tightening Otto's restraints that kept the device around his face.

He doesn't like that, not one bit. So, me watching he takes the knife to her, laughing while he does it.

He had been unable to do anything but smile as the triumphant gleam in Wing's eyes turned to horror as the man straightened up with a sickening crunch and pulled the shard out of his own chest before plunging it into Wing's.
"No!" Wing shouted ignoring the blood streaming down his chest, "You must keep smiling Otto. Promise?"
He hit the floor with a sickening thud and his own mouth turned upwards into a peaceful smile as his brown eyes stared unseeingly into Otto's own.

He turns to me and he says "WHY SO SERIOUS!?" He comes at me with the knife "Why so serious!?"

Through everything that the man put through, no matter all the people that he was forced to kill Otto kept smiling in hopes that at the very least Laura would be released safely to him. But it wasn't to be. He found her, curled up at the bottom of a vat of acid… the same vat that he had fallen into while running away from the boy that was trying to stop him… stop him from keeping her safe. Or at least he thought it was her.

Sticks the blade in my mouth, "let's put a smile on that face!" aaaand…

Now he had a new purpose in life. Just like Doctor Nero had said: I'm training you to be the most evil you can be.'
Well he was going to fulfill their wishes and keep the last promise he made to his first friend at the same time. Stretching he dislodged the redhead who had been lying in his lap and he traced his fingers over the self-inflicted scars at either side of his mouth that were traced up in a hideous mockery of a smile. He would always keep smiling, and he would make sure everyone else did as well. For what else could the Joker do but make people smile? With his precious Harley by his side of course, but she could never replace the ones he had lost. Harley was his precious Laura; Batman reminded him of Wing, always so righteous (but he wasn't smiling why wasn't he pleased for what Otto did for him?); all the other faces he saw reflected in the mindless drones that inhabited Gotham.

Soon they would all be smiling and maybe then Otto could sleep in peace. Maybe then. Maybe.

WHY SO SERIOUS?