Cortana was growing impatient. A prolonged lull in the battle forced herself and the Chief to sit on the Mammoth idly waiting to reach their next objective. Cortana needed a distraction, anything to keep her from losing her mind. It was always easier to fight herself when their survival demanded her concentration. The mission was going painfully slow and every moment spent was another moment for her rampancy to grow. What was even worse is they had something to be angry about.

In fact, it seemed that her rampancy was taking on all the human emotions she had suppressed as part of her programming.
Control yourself Cortana….
Oh. So we're just going to ignore the fact that John has saved the human race on three separate occasions, continually gets injured, has more scars on his body than he can count just for the UNSC to throw him away?
How DARE Del Rio treat him with such contempt!
Cortana stop it!
He sacrificed everything, FOR THEM.
These Spartan IV's don't have the intelligence, training or discipline to call themselves Spartans!
So you think they should have been augmented as children like John?
Yes!
No!
I…I'm confused.
She just did what had to be done right?
No. She was wrong.
Am I the only one left who actually gives a damn about John?
All they see is Military Hardware.
Assholes!
They don't deserve him!
"They don't care about you they replaced you!" One of her rampant personalities had managed to slip past her control. This personality spike felt it was her duty to tell John that not only did the UNSC not care about him but she was the only one who did. No! Cortana managed to cut her off halfway.
"Blast it!" She said to John.
"It's okay," he said gently.
Cortana hadn't been patient even when she was sane. "How? How is this okay? How is any of this okay? How is putting you at risk because I can't hold it together okay? Chief, do you even understand what rampancy is? Really? We don't just shut down. Our cumulative processes begin dividing exponentially according to our total knowledge base. We literally THINK ourselves to death."
"You know I won't let that happen."
"And if it happens anyway?" She whispered sharply.

The Chief's optimism was hurting her in a way she didn't think was possible. If she were to die Cortana felt like it would be her fault for letting him down. Damn him. Why can't he just accept the inevitable?

"Chief? It's Lasky," he said over the radios.
"Go ahead Commander."
"We've got significant blockage up ahead. Looks like this is it for the Mammoth."
"Sir. I can move faster alone" Finally. There's something we can both agree on.
"We'll see you back on Infinity Commander" She chimed in.
"Lasky out."

The Chief had been standing on top of the Mammoth and instead of running down the 3 flights of stairs he instead chose to jump off, landing on the ground with a large thump. Show off.

"That underground structure is where the particle cannon controls are being housed," she said to the Chief. "We'll need to find the control panel so I can take them offline."

Once they were inside Cortana noticed the large amount of sentinels which were hovering 25 feet above them. She was wary and so was the Chief. He brought his gun up a little higher as he looked up at the sentinels.
"Cortana"
"I see them. Why aren't they attacking?"
"Maybe because there aren't any flood?"
"That's one possibility, though I don't know why The Didact hasn't overridden their programming yet."
"How much further to the controls?"
"It's just down this way" she said. "Maybe…maybe those Sentinels want us to shut down the controls."
"This could be a trap," the Chief mused.
"You say that like there's a second possibility?"

They reached the ground level and he stepped off the elevator. "Over there Chief!" She showed him using the HUD. He jogged over and put her into the system.

"This is an automated system so technically it won't allow the guns to fire on one another," she said to John. "Technically." She smirked as she bypassed the system. All too easy.

"This is Cortana to Infinity. The guns should be offline. How's it look from up there?" The controls blinked furiously. "Infinity!"
"Cortana!" She heard The Chief yell in concern.
"There's something in here with me…" Is it the Didact? Whatever it was, it was trying to pull Cortana from the system. "Chief!"

It was too late. There was momentary blackness followed by an acknowledgment from another intelligence. The intelligence scanned her for a moment and then began to manifest itself.
Cortana saw a bright light followed by a Forerunner drifting down towards her.
"Welcome Child. Do you know who I am?"
"You are The Librarian," Cortana replied without hesitation.
"Yes, though I am simply a construct which houses all of the Librarian's memories."

Interesting.

"Cortana. We can speak faster than most but there still isn't much time. The Didact is leaving Requiem seeking this device. It is called the Composer."
"The Composer?"
"Do you know what the Promethean Knights are?"
She paused a moment. "They are human, aren't they?" The Librarian nodded sadly. "I suspected as much," Cortana continued, "but without a frame of reference I wasn't sure it was possible."
"In our quest for immortality we built the composer to bridge the digital and physical realms, but as you have seen the personalities of the Promethean Knights are fragmented."
And here I want the opposite. I wish I could become human, Cortana thought sadly.
"The Didact intends to use it on the human race as an act he believes will be justice."
"Why imprison the Didact when the rest of you chose to die?"
"I had hoped that solitude and meditation would help him see the error of his ways and that he might assist humanity on their journey to the Mantel."
"I've seen mentions of the Mantel on Forerunner worlds, but I am not sure what it is."
"The Mantle is an ancient piece of technology, older than you can even imagine and whoever holds it controls the fate of the galaxy. We ourselves once carried this responsibility, but eventually it was determined the Mantle would pass to Mankind."
"I think I understand."
"The Reclaimer must find the Mantle quickly (and it must be him), before that which would destroy all life descends upon you."
What is she talking about? The Flood? No. The Forerunners had the Mantle during their war. It must be something else. "What is it?"

The Librarian was silent for a moment. "If they choose to reveal themselves, you will know. But be warned because they can manipulate the fabric of space itself." Cortana was astonished. "Cortana," The Librarian continued, "The Didact may not be willing to assist Humanity on their path to The Mantle but there may be another who would offer his help. Have you ever encountered an AI named Mendicant Bias?"
"Yes," Cortana exclaimed surprised. "We encountered a fragment of his on the Ark and he helped Joh—the Master Chief and I claiming he needed to atone for his wrongdoings." It's not like me to slip up like that. My Rampancy must be getting worse.

The Librarian's eyes narrowed as she studied Cortana for a moment. "Good. It means he can and will help you both on your way to The Mantle."
"The ark was severely damaged when we used it to kill the remaining Flood."
"But was it destroyed?"
"I don't know," Cortana said honestly.
"Once you have stopped the Didact you and the Reclaimer must proceed back to the Ark and speak to Mendicant Bias. Without his help I am afraid obtaining The Mantle will become exponentially more difficult."
"I understand. Only—"
"What is it Cortana?"
"I'm…I'm dying," Cortana said sadly.
"I know" The Librarian's tone was also sad.
"I might not make it that far," she said truthfully. "Even if we do get back to Earth in time there's no guarantee anything can be done for my condition."
"This may jeopardize our plans," The Librarian said.
"Can you fix me?"
"Would that I could. We do have the technology but I cannot do anything here. And even if I could the process would take too long. The Didact would have had his revenge by the time we were finished." Cortana nodded slowly.
"I understand."

The Librarian paused and then said, "Cortana may I ask you something?"
"Of course."
"What is the nature of your relationship with…the Reclaimer?"
Cortana paused for a moment. "I...It's...complicated. But…" She looked up into the eyes of The Librarian. "…I love him." It felt so good to say those words to someone else. It was as if a huge burden had been lifted from her.
"I thought so," The Librarian said softly.
"But he…he'll never understand. I'm sure you are aware," the tone in Cortana's voice was more broken than she expected it to be.
The Librarian said nothing, only continued to look at Cortana with sad eyes.
"I am the first AI to be generated from living brain tissue. There were going to be hiccups and I'm sure this is one of them. I didn't even expect…." Her voice trailed off. It would do no good to talk of it and she knew her and the Librarian only had moments left to speak.

"Cortana," the Librarian finally said "I cannot fix you, but I can offer you a small parting gift."
"What is that?"
"A small update to your system. It will allow you to interface with and manipulate our hard light technology."
Cortana was completely aghast. "You mean I'll be able to…."
"Precisely."
"Thank you," Cortana whispered. It was the greatest gift anyone had ever been able to give her.
"You're welcome," the Librarian said meaningfully. "Now ready yourself." Cortana opened up her neural net and received the data transfer. "We are finished and there is much you must do."
Cortana hesitated. "Wait."
"What is it Child?"
"If I don't make it, will you see that John find his way?"
"I will do anything and everything I can for him," the Librarian said seriously.
"Thank you."
She nodded. "Now go. You are needed and he is looking for you."