I
The Batman grabbed at his utility belt for one of the grenades Mr. Freeze gave him. He felt only one left. Grabbing it instantly, he threw it straight into the maw of what was once Basil Karlo, freezing Clayface instantly. Wasting no time, Batman ran to Karlo, climbed up, and pulled Talia al Ghūl's sword out of the frozen mass. He could see the ice already melting. Wasting no time, he jumped into the frozen mouth of Clayface just as he unfroze.
Karlo looked around, confused, when a blade was jabbed out of his stomach. Clayface looked down in awe, as the blade slipped back in and was used to cut a slice between the head and shoulder. As Karlo gasped in defeat, Batman leaped out of the mess of clay and sheathed the sword. He held in his hand the vial containing the cure. Batman raised the test tube to his mouth and drank half.
"Out of my way, Bats! I've got a date with immortality!" Batman swiveled to see Joker standing over the Lazarus Pit. Acting fast, he grabbed the sword and swiftly threw it into the control panel, barely missing Joker.
"No!" Joker screamed. The generator swung down barely above the pit, pushing Clayface into it, and henceforth triggering a massive explosion. Batman clenched the cure and was blown backwards.
Batman awoke, he estimated five minutes later. He heard Joker's raspy voice, "Quick! The cure!" Batman looked at his hand, seeing that the cure was still there. "What are you waiting for? C'mon!" The Dark Knight stood. "I killed your girlfriend, poisoned Gotham, and hell! It's not even breakfast! But so what? We all know you'll save me." This time, Batman responded. "Every decision you've ever made ends with death and misery. People die. I stop you. You'll just break out and do it again." Batman turned. The rasp returned. "Think of it as a running gag!" As he said gag, Joker came out of nowhere and stabbed Batman in the shoulder, causing Batman to drop the cure. "No!" Joker screamed. He ran to the puddle of blue liquid and frantically slurped at what little was left.
"Are you happy now?" Joker asked. "Do you want to know something funny?" Batman asked. "After everything you've done… I would've saved you." Joker cracked up in raspy laughter. "That actually is (cough) pretty funny." Joker lost all strength and deeply exhaled. And did not inhale. No! Batman thought. He blinked twice and entered a world of numbers and statistics.
Batman focused his attention on Joker's limp body. 19 bpm… he's still alive! Batman grabbed Joker's body and grappled up to the Monarch Theater, still splattered with specks of clay. He ran to the door and kicked it open, where Joker's goons were located. "Move it, bozos!" said the voice of Harley Quinn. "No!" she said when she stood directly in front of Batman. "Y-you KILLED HIM!" she screamed. "Move, Quinn." the Dark Knight coolly responded. "He's still alive. I need to get him to Freeze now!"
"Wha-" Harley was cut off as Batman grappled up to the top of the theater in one fluid movement and raced across the rooftops of Arkham City. He would save Joker. He had to.