There were two types of heroes, the vigilantes who pretended to be heroes, and the actual heroes. For Jason, he was just a child trying to play vigilante, trying to go toe to toe with someone that he thought he was capable of defeating. But the truth was; Joker was not like any other criminal that Batman had ever fought before. There was a reason why men strong enough like Bane or smart enough like the Riddler were no match for him. There was a reason why Joker excelled over all the others, and it was because he had no reason to do the things that he did. He just did them. In the grand scheme of things, this was a man who was no longer a man, but a pure psychopath who wanted to watch the world burn. And he would burn all those who opposed him.
For days now Jason fought. But there were times when Jason's body would reach the end of it's strain, and he would call out for his beloved "father". The same father who left him there to die. The same father who threw him into this world of psychopaths, gave him a suit to wear, and the belief that he could be something more than an expendable pawn. It was Joker himself who would dismantle that belief, torturing the boy until he was begging for death.
"He'll come.." Blood spat through gritted teeth, through tough words. It was cute, how he believed that. How he believed, even after all this time. He still had hope.
Joker laughed, wiping the spit from his face. "Batsy! Batsy! Woo-hoo!" He waited mockingly for a voice in the shadows, waited for what he knew would never come. "Nope! No Batsy here, just you and I. Don't ya love it?"
Blood dripped down onto the concrete floor. Each drip adding to the puddle underneath the chair. Jason's one eye was swelled, bruised, and his face was littered in cuts. He was completely unrecognizable. He still wore his trademark suit despite how torn it was.
Jason's good eye clenched shut, and Joker knew damn well that the boy was fighting that dread. But it was inevitable that he would come to realize that he was truly alone. That the one man who swore to protect him could not even do that. Bruce Wayne, Batman, his father, his mentor, his friend, could not be his savior. It was that moment of sweet surrender, that moment Joker had been waiting for.
Through those last few days Jason had been beaten with batons, cut with knifes, carved into like a piece of meat, and electrocuted with cattle prods. That smart-ass Batboy was nothing more than a quivering mess now, within the last inch of his life, and knowing that was why Joker released him from that chair, letting him fall to the ground by Joker's feet.
"Get up." He ordered the boy. "Fight me. Kill me. I know you want to. You know he's not comin' for ya! Ya know it's all on you. Come on, boy. Kill me." He antagonized the bird, knowing that Batman would have done everything in his power to make Jason just like him, to keep him from killing anything. But Joker had to believe he molded that boy into something else entirely. He was no longer Robin. He was no longer the boy underneath Batman's wing. He was his own creation. A creation that would either kill to save himself or die for the last remaining piece of his old self.
Jason shakily stood to his feet, surprisingly enough. He fought. Hell, he'd even thrown in a few punches, but Joker knew he had an advantage. The boy was far too weak and the impacts of his fist to Joker's flesh showed it. Eventually Joker grew tired of the game, and as Jason fell to the floor, his breathing shallow, raven-colored hair clouding his features, Joker knew he was done toying with him.
The crowbar hit his back with a sick crunch as bones shattered from the impact. Again and again, Joker brought his arm down until the little bird stopped moving. His breathing stopped, his body still as death itself. But despite the fact that Joker knew the boy was dead, he continued, laughing manically as blood spurted all over his ghostly face. Soon that crowbar would make a dent into the boy's skull, clumps of brain matter sticking to the hilt of the crowbar.
Thoroughly satisfied with Todd's defeat, he would leave the mangled body of the former bat to be found in Gotham's Square. When daylight broke through the clouds, and people would crowd around completely unaware of the horrors that would await, Joker would give his greatest gift to Batman.