"Have you found what you're looking for?" Clark asked. He had shaved his face, gelled his hair, and donned his flashy red and blue uniform. He was looking exactly like Superman from Bruce's time.

"I just got here five minutes ago." Bruce grumbled. He pressed the power buttons on all his computers. A rumble of electronic noises reverberated across the Batcave.

Evidently, Kryptonians experienced five minutes very differently than humans. Clark drifted up along Bruce's shelves and scanned the titles. "Where is the section on time travel?"

The lack of response from Bruce was somewhat disconcerting. Superman frowned. "Bruce?"

"It didn't exist."

Clark turned to look at Bruce in puzzlement. "But you said…" Batman owns the largest collection of time travel theories.

"I lied." Bruce was still watching his screens come to life. Most displayed interfaces that he had never seen before. Technology advancement in thirty years was staggering.

Clark lowered himself to the ground. There was an ecstatic lilt to his voice when he spoke. "So does that mean…" That you cannot go back? He immediately berated himself for the hope that was growing exponentially at the back of his mind. The hope selfishly founded on the impossibility of time travel, rather than Bruce's willing choice to leave or stay.

Bruce turned to regard him with an expressionless face. "No. I said 'did not exist'. In my time, time travel was not a priority. It was an interest, a hobby. I cannot say the same for my older self."

Clark's smile cracked at the discovery. "I see." He muttered, glancing at the shelves that stretched across the Batcave. "I'll start searching."

Bruce spent the next hour going through the documents on his computer. There was a huge, frequently updated database on Kryptonite-induced cancer. Yet it was immediately clear to Bruce that despite the massive database, there was still not enough information. Because everything the older Bruce gathered was theoretical. There were no historical precedents of the disease. He needed information from a dead body.

Bruce almost jumped when a finger tapped his shoulder.

"Sorry to startle you." Clark grinned sheepishly. "I found something that might interest you."

They traveled to a new section of the Batcave. It had been expanded by almost two-thirds of the original, its walls all lined with containers. Clark stopped at one of the dusty shelves and pulled out a cardboard box.

"Blueprints." He explained. It was filled to the brim with rolls of schematics.

Bruce unrolled one and read a drawing with furrowed brows. "Construction drawings. Detailed to the product name, dimensions, and protective coatings. This is something ready to be built." He glanced at the title block. It was empty. No title, name, or date.

"Or it has already been built." Clark was looking at the wall that was behind the box. He activated his x-ray vision to find that it was not lead-lined. His Bruce was not deliberately trying to hide the contents from Superman when he built it. Clark turned to Bruce for permission.

Bruce nodded. "Burn it."

Clark traced the wall with heat vision, carving out a large hole. The painted concrete crumbled and fell to the ground. Inside was a tunnel.

"I'll go check." Clark volunteered. He crawled into the hole before Bruce could protest. The tunnel was dark, but short. It led up to a larger hole, where he found a heap of used metal. He carried the mountain of leftovers out to the cave.

"Don't know what this is, but it's all that's left in there." Clark dumped them onto the ground.

Bruce picked at the smaller pieces. "You're right." He frowned, clamping the schematics with his feet across the floor to keep it from rolling up. "The machine corresponds to the drawings. But for whatever reason, it has been destroyed."

"Deliberately?" Clark asked worriedly. He eyed one version of the Batsuit hanging in a glass container nearby. He was suddenly reminded of the older Bruce. Bruce whose mysterious beauty was defined by all that he chose to reveal and not reveal. What secrets have you been hiding from me?

"No." Bruce inspected the uniform scorch marks on a larger piece of metal. "Overheating. The energy flow was too great. As great as time travel."

"You used it." Clark blurted out. At Bruce's stare, he scratched the back of his neck in embarrassment. "He built the machine to travel back in time, then it overheated and exploded."

Bruce nodded slowly. "We won't know whether his travel was successful. But the end result is the same." He skimmed through a few more schematics, then he glanced at his watch.

"We should go back upstairs."

"Okay," Clark eyed the box he was carrying. "Do you want me to...?"

"Yes, put it on my desk."

"All right."

"Wash your hands. We're going to cook up a storm."

Clark lowered the schematics on the table and blinked. "You're expecting guests?"

"A dozen of them." Bruce replied. "Worst case scenario, we'll order takeout. No one has to know."

He turned away with a mischievous wink, lending Clark the same momentary illusion that his world was as complete as it was years before.