Onward with the fic! :D :D

A word of warning, there is a flashback of a character death. You have been warned.

John watched quietly as Cortana moved from one control panel to another. Her hands were steady, her emotions less so.

John couldn't say he was much better.

Though this was the best he had seen her in a long while, he knew she was still losing the battle.

And the Chief hated losing.

John forced him not to think of Cortana's failing health and focused on his main objective of reaching the Halo ring.

If Captain Picard would not allow them to transport to the surface, John was certain that between his might and Cortana's familiarity with the Enterprise's computer systems, they could commandeer a shuttle and make it to the Halo ring with relative ease. The officers stationed aboard the ship were not soldiers and he could use that to his advantage.

For now, he was content to allow the captain to deliberate about his next course of action while Cortana continued to work on repairing her program.

"I have cleared most of the redundant data from my memory banks," she said. Something akin to hope was reflected in her eyes. "It's going to take some time for me to sift through all the Forerunner and UNSC data, but I think I can have full access to my own personal files."

John wasted no time to allow himself to hope. He simply nodded. "Do it."

"When I implement this protocol, my program will go offline. I am going to need you to reactivate me after thirty seconds. We'll know if it works then." Her hand hovered above the control panel. Then, she pressed the button.

She was gone again.

Despite her warning, John's gut tightened at her disappearance. After weeks of waiting and hoping, he had just got her back. He didn't want to think what would happen if he couldn't reactivate her.

Pushing his feelings aside, he counted to thirty. Then, he reached over and activated the button. Three seconds passed.

Nothing.

"Cortana? Are you there?"

"Give me a second." She sounded distracted.

Finally, nearly a minute later, she appeared in front of him. A soft smile was on her face.

"Did it work?"

She nodded. "I remember almost everything of my own history. I remember that day that I saw your picture on Doctor Halsey's wall, thinking how handsome you were-" John felt a blush crawling over his cheeks. "-and I remember that I chose you to be the Spartan I would work with."

She moved to stand directly in front of him. "I remember the Autumn, and Halo, and Cairo." Her gaze shifted downwards. "I even remember High Charity with him. And I remember you keeping your promise."

"And Requiem?"

She gave a small nod. "The data was fairly corrupted, but I managed to splice enough of it together to get a good idea of what happened there." She looked up into his face. "But after the Composer..."She let out a soft sigh. "...there's not much to work with. I had to use the data from your armor's databanks to fill in the gaps."

"But you remember more than you did."

"Yes, but John..." She placed a hand on his chest, like she had. Before. "The Rampancy is still corrupting my systems."

This was the best he had seen Cortana in years. He was not going to let this opportunity slip away from him. Not like it had on Requiem. Before he had a chance to respond, the doors to the holodeck opened. Captain Picard stood on the other side of them.

He had stepped back quickly when he saw the commanding officer. Cortana's hand dropped awkwardly to her side.

If the captain saw anything, he didn't make a comment on it. He studied the two of them of a second before he spoke. "I have decided to authorize the two of you to beam down to the planet's surface. An away team led by Commander Riker will accompany you. But, first, I'd like some answers."

John exchanged a glance with Cortana. "We cannot tell you anything about the future."

"I understand that, but I would like to know about where and when you came from. I want to understand why you are here and why this mission is so important to you."

Cortana let out a shaky sigh, giving John a sideways glance. "I guess we owe him that much." She closed her eyes briefly.

"When the Chief and I were first assigned to work with each other, humanity was being attacked by a group of religious zealots called the Covenant. Humanity was fighting a failing war. One ray of hope we had was a group of soldiers called Spartans." She nodded her head towards John. "Despite their best efforts, our home world was attacked and destroyed. We were forced to flee. Our ship left the system and we found ourselves at a Halo ring. And there we found something far more dangerous than anything we had ever encountered before."

A infected form of the Flood appeared in the center of the room, frozen in time. Although John knew that it was a holographic projection, his pulse still spiked.

Cortana's voice remained calm as she explained what the Flood were, why the Halo array was created and how Earth had been nearly consumed by the Flood. But, as she started to recount what happened after the two of them were stranded in space for years, her voice started to sound more panicked.

John offered to take over the rest of the narrative, but Cortana insisted on telling their history.

"The Composer was a weapon of mass destruction. It would have killed everyone on Earth, but the Chief stopped it." She offered him a shaky smile.

Picard, who had been silent the entire time, frowned. "But that doesn't explain how you got here."

John finally spoke. "We're here because I failed in my objectives."

The plan was simple. After the destruction of Requiem, ONI studied the piece of the map that Thorne had held onto that contained information about Forerunner installations that they had yet to encounter. After reviewing the map for nearly a year, ONI had made a discovery. The data -the minds of those who had been taken that day in New Phoenix- had been siphoned to a facility known as the Cache. And there was evidence that Cortana's program had survived the destruction of the Composer.

John had immediately volunteered to go to the installation. Thorne, and the rest of Fireteam Majestic, had asked to be part of the mission as well. At the beginning, everything was going according to plan. But then, they had found her.

Halsey.

She had been dying from a gunshot wound to the abdomen. Then, she had explained how this had been a trap and how the Didact, obsessed with the destruction of humanity, had made a deal with the Gravemind who had been slowly rebuilding after he had nearly died when the Ark had been destroyed.

She had slipped him a chip which held a fragmented Cortana. "It is the best I can do, John. Take care of her." Then, Halsey had died.

She had been the first of many casualties that day.

The UNSC, Separatists, Covenant and Insurrectionists worked together to fight against the impossibly powerful enemy. In the end, only a scant few million hadn't been infected.

"Our universe had been overtaken by the Flood." Cortana's voice cut through the memories. "The Infinity was the last UNSC ship and we knew we could only run for so long. Then, after 18 months, the Gravemind found us."

Lasky, Palmer, and the others -even Roland- had been consumed by the Flood within hours. Trapped in a storage bay with a shotgun and less than a dozen shells, John had finally allowed himself to concede defeat.

But then, before the Flood could attack, a portal had opened inside the bay. Without hesitation, John had jumped in with Cortana's chip in his armor.

"We managed to escape, thanks to the Librarian." Cortana's voice was strong. "She was from the Foundation. The original timeline where all possibilities begin. There, she offered us a deal to do what we couldn't do in our own time."

"Save humanity." John's words hung in the room.

Picard's eyebrows rose. "Then, this isn't the first time you've traveled to other universes."

"No. We've dealt with everything from Cylons to Ancients." Cortana's chin jutted forward. "Someday, we're going to save our people."

"How?"

"By finding a cure for the Flood infection."