A/N: I try to envisage the characters with their most memorable voices from all media, so picture Batman, Joker and Red Robin with their Arkham City voices and our cameo stars with their HBO TV Show personas.

Prologue

"Now let's see... a dash of that... drop of this... HA HA HA maybe even a pinch of whatever we have here...ohh this is going to be delicious, hehee!"

ACE Chemicals. 3am. A purple dressed figure is dancing around a vat of chemicals, brewing up a heinous concoction of toxic waste and all sorts of unknown ingredients.

"MR J!" screeched a high pitched voice.

"What is it poo?" replied Joker.

"Bugsy and Big Top aren't answering the radio."

"OH NO! WHAT WILL WE DO?" he muttered sarcastically.
"I smell flying rodents too." Harley squawked, holding up a bat-shaped metal projectile she'd found on the floor. Joker stared at Harley, pondering his next move.

"Deal with it. Now." His voice was unusually cold, even for him... Harley ran off down the hallway.

"You two! With me!" Harley ordered two henchmen as she disappeared into the darkness.

Joker paused for a second. He didn't know what to do. He'd only just escaped from Arkham and was building up for a Christmas prank. It's September! What will he do? Suddenly, two henchmen patrolling the outer walkways were taken into the darkness... funny thing was, they were on opposite sides of the room.

"He's not alone Harley! He's brought a bird with him!" Joker shouted, with a little more anxiety in his voice than usual. SMASH! The window behind him shattered into pieces as Red Robin jumped through it. He landed with swoop of his bowstaff and knocked out the henchman behind him. As Joker searched for a comical opening line, the skylight above him came down with a thud and crashed into his concoction of chemicals. Standing on top of what was left was the Bat himself.

"Sorry Bird-Boy, his was better!" Joker said, secretly pleased with the line.

"Enough!" Batman retorted, "Where's Detective Montoya?"

"Oh she's right over there." Joker pointed at a shadowy box, with only just enough light upon it to make out that it was a glass box... with the detective inside. She was clutching one wall of the glass prison with a look of fear that even Batman would feel for. "Lights, Harley!" Joker shouted. As the light filled the room, another glass box appeared next to the one Montoya was in, and this one contained a tiger. It could also be seen that there was a door in between the two. "Now if you so much as sneeze I unlock that door and the good detective hear becomes a carcass in the corner."

"Why Joker?" Red Robin asked.

"She's done me a great injustice." Joker heartily replied.

"Which was?" Batman replied through gritted teeth.

"She QUESTIONED me." Joker replied before cackling manically. Batman was taken aback. How could he know this?

"If you think I'll let you run..." He said, advancing forward.

"Whoa whoa whoa! Hold the phone, operator! One more step and I'll press it." Joker warned as he pulled out a remote control from his pocket. "You know I'da thought you of all people w.." Joker was stopped as the remote was knocked out of his hands. "Wha?" Joker stared at the remote, skewered on the wall by an arrow. "Shouldn't you be in Star City?" Joker turned to see a figure standing in a window.

"You stole from Queen Consolidated's applied sciences department. I wanted to follow up the lead." Replied Green Arrow.
"I knew you'd eventually show up, hood boy, so I brought along some protection. Oh mister Wilson!" Joker said as a Joker goon removed his mask to reveal himself to be Deathstroke. He charged towards Arrow who had leaped down to ground level, bow primed and ready. The two began to battle, both showing their prowess in hand-to-hand combat. Deathstroke made his attacks with his sword, while Arrow decided to use his bow and a melee weapon. Meanwhile Batman and Red Robin moved towards Joker as the clown watched the duel take place. Batman drew a batarang from his belt and took aim. Joker turned sharply towards them, a bloodthirsty grin on his face.

"Nice try, but you of all people should know I always have one more trick up my sleeve." He said, gesturing to his right hand. As Batman quickly examined Joker's right hand, he was struck in the face by the left, and he felt a twinge in his cheek. He looked up to see Joker holding a mini-syringe in his left hand, but he was quickly wrestled to the ground by Red Robin. "I'll visit you in Gotham General, Bats!" Joker laughed. Batman lay on the ground, clutching his face. He could taste blood, but there was something else in there too. He spotted the batwing hovering above the open window, and shot his batclaw up to hoist him into the cockpit.

"Leaving the party so soon?" Joker said with a hint of sadness. Batman pulled himself into the seat of the batwing, blacking out only after seeing Red Robin lay a few blows into Joker's white skull.