First, during the season 1, introduce a down-on-his-luck comedian who cant get a laugh. Show his day from start to finish. His father is an ******* and a drunk and nobody gives him any respect. The only person in his life that cares about him at all is his girlfriend, whos very supportive of his career, perhaps even being the only person who laughs at his jokes. That night, when he leaves the club hes performing at, hes attacked. His girlfriend is murdered in front of him. When the killer looks over at the comedian and sees his expression, the killer tells him that he should smile more, before slicing the sides of his mouth. When the victim is introduced to Detective Gordon, his name is revealed to be Jack Whiteman.
The episode should end with all clues leading to dead ends. Jim tells Whiteman that they havent found the man yet, but will keep looking. Whiteman responds by saying something to the effect of: You know, its ironic. I spent so much time trying to get a smile out of people, but never smiled myself. Now, after all of this, after losing the most important person in my life, knowing that the man who took her from me is going to get away with no repercussions, *gestures to cuts on mouth, dramatically* NOW, I cant stop smiling. *Insane laughter*
Let people wonder whether Jack Whiteman is one of the Jokers first victims, or the man who will one day become the Joker. With ending of that episode, there will probably be more people who think Jack is the Joker than people that think the killer is.
In season 2, introduce a new character, a hitman who wears a red hood. We should see the man out of his hood a few times. At least once should be him playing a game of poker, to make a few peoples minds move in that direction. Once should be with his family, a wife and a son, somewhere between the ages of 2 and 6. The police will be searching for the hitman, who they have dubbed The Red Hood, due to their case in this episode, but will be unable to find him by the end. The Red Hood should appear a couple more times during the first half of the season, but mostly in small roles.
Then, later, we see Jack Whiteman again. Theres a serial killer in Gotham now who leaves joker playing cards on top of the bodies of his victims. The first worked at a comedy club. Nobody initially realizes that its the same one Jack Whiteman use to work for, until Jacks father becomes the second victim. Jack quickly becomes the prime suspect, and is arrested. Jim can see that Jack has clearly gone mad after the death of his girlfriend, and its not unreasonable to think hes started killing people who he feels have wronged him. Then, the next body drops. The police realize that The Joker Killer, as they are now calling him, is the man that attacked Jack Whiteman and is trying to reach out to him by killing those that did him wrong. In this latest murder, theres a witness who says that the man who did it was wearing a red hood. With this information, along with other clues that were at the crime scene, Jim is able to learn the identity of the red-hooded man, who they believe to be The Joker Killer, and the police search his home. By this time, the Red Hood is already gone.
At the end of the episode, the Red Hood makes a phone call to his wife, confessing to her that he was a gun for hire, and was getting paid good money to kill these people and place the cards over their body by an anonymous employer. He tells her that he believes the man that paid for these hits wanted him to take the fall for a past murder (that of Jack Whitemans girlfriend) as well as these ones he committed, and manipulated the investigation to lead the cops to him. Finally, he gives her the bank account number where he kept the excess money he made from his jobs, asking her to use it to take care of their son, Jason.
Theres another long break before we get back to the Joker storyline. This will be a two-part season finale. The Joker murders have begun again, this time, random people, random methods of killing. The only thing any of them have in common is that a joker playing card is left on their bodies. The first episode is the investigation into the murders. Jim and the Red Hood are both searching for him, though Jim still believes the Red Hood is The Joker Killer. However, their investigation is dangerous, because Joker has stepped up his game, now rigging his crime scenes with deadly traps. Toward the end of the episode, we see the Gotham PD figuring out where Jokers hideout is. Then, we switch to a scene with the Red Hood confronting Joker. When the police get there, the Red Hood is dead, with a joker playing card on his chest.
Next, Jim gets a phone call from Joker, taunting him, before asking him if he wants a second chance. You tried so hard, wasted so much effort on trying to find me, all for nothing... You know, I could give you a second chance. Would you like that? New evidence, fresh clues. It could be fun. Would you like another go at me? Without fully comprehending the Jokers meaning, Jim say yes, then you hear him cackling, followed by the sound of glass shattering one of the officer behind him (a love interest, perhaps?) gets a bullet in their head.
In the following episode, they realize it was a sniper from a nearby building that took the shot, but by the time they get there, the sniper is gone. Perhaps another officer is killed by the traps in the building. The rest of the episode is Joker running away from the police, leading them to an abandoned funhouse that hes rigged with with traps more deadly than any at his crime scene. Here, Joker is God. Knowing where all of his traps are, as well as how to trigger them, hes able to pick off the cops one by one, using everything from explosives, to bear traps, to laughing gas. Jim finds the Joker, has his gun locked on him, but Jim sees that hes only a kid, about nineteen, and, even after seeing so many of his friends die by this madman, doesnt have the heart to kill him, giving Joker time to escape.
For the time, the Joker killings stop. When they begin again, it will turn out to be a copycat, Jack Whiteman, whos being guided by the actual Joker. At the end of the episode, Gordon is chasing Jack across the roof of a building, when Jack falls off into a vat of chemicals. For a few minutes, at least, you shoul think that perhaps Jack is the REAL Joker after all, before the police drag his body out of the chemicals and find that hes completely and totally dead. In memory of his fallen ally, and first success at destroying a mans soul, the Joker later begins using the alias, Jack White.
From this point on, the Joker episodes can largely be about how he created his criminal empire, with both the Red Hood and Jack Whiteman storylines killed off. The police will try to learn his identity, and hell troll them, leading them down false trails. We will slowly see him become more and more bold after the funhouse incident, moving on from just murder to elaborate schemes, manipulating the criminal underground and turning into the Joker we all know and love.