Bat Serum

Splat!

Joker had Batman strapped to a cross. With a scalpel in hand, he slowly peeled Batman's skin away, continuously stitching him up to keep him bleeding. His organs lay exposed, and Joker tore them apart bit by bit.

"How is it, Batman? You're definitely going to love this!" Joker laughed maniacally, his voice shrill and mournful. He had fallen into a frenzied, fanatical state, using every method he could to cruelly torture Batman.

"Big Bat, I destroyed an entire universe as a sacrifice for you. Do you like it? Watching all those lives receive the exact same treatment you're enjoying—does that make you happy? Hahahahaha..."

Drip, drip...

Drop after drop of blood gathered into a river. Batman's mind had long since fallen numb, yet his eyes remained fierce. Enduring the agonizing pain tearing through every part of his body, he stared coldly at Joker.

"I'm keeping track of every debt you owe, Joker. I'll remember every single person you killed."

Batman was not angry for himself. He was angry for those innocent people who had died.

No one could imagine what Batman had gone through during this time. In this world where time had lost all meaning, he had watched Joker slaughter life after life, watched universe after universe repeat in cycles. Countless horrific scenes and endless miserable screams filled Batman's mind.

Joker had been relentlessly twisting Batman's will this entire time. Perhaps a hundred years had passed, perhaps a thousand, perhaps even ten thousand. Joker had always used every cruel method imaginable to try to corrupt Batman's resolve. He wanted to prove it to Batman, and to the world: even the Dark Knight would eventually yield to the darkness in his heart.

"I love that look in your eyes!" Joker said. "It gives me such a terrifying feeling.