How much of Cortana made it to the Domain?

At the end of Halo 4, in the final level, Cortana seemingly makes copies of herself in order to lower the Didact’s shield around the Composer so Chief can get in there to denote the Havoc nuke. But what I think is that, instead of copies, those were actually fragments. I say fragments because in her ending speech with the Chief, she said “Most of me is down there. I only held enough back to get you off the ship.” Furthermore, we know from the extended universe that during the events of Halo Reach, the Cortana given to Noble 6 was a Cortana that was managing the Forerunner tech under Sword Base, that was reunited with the Cortana on the Pillar of Autumn after Noble 6 delivered her to Keyes.
So what I’m wondering is two things. 1) Is Cortana copying herself outright, or fragmenting herself in these cases? I feel like complete copies would be a bit OP and confusing; she could copy herself as many times as she wanted to exponentially increase her processing power. And would the copies be permanent? How would a complete copy know it was a copy and not the original? I want to believe that she instead fragments herself, creating partitions. I mean, otherwise, if it were a copying ability then there is no reason why the instance of her that saved John off the Mantle’s Approach couldn’t have stayed with him. 2) Assuming that only a fragment or incomplete copy made it through slipspace to the Domain, how much of her can we assume made the journey? I expect that this may be answered in the next Halo, but I’m wondering if any lore experts have any insight now.
I know the Halo wikis state her power is “cloning” herself, but again I feel like there are issues that come up with being able to make full clones as opposed to partitions. But since I don’t know for sure, I want to pose this question to the community.

Cortana does make copies of herself. She learned how to do this in Halo: First Strike.

Halo: First Strike (Definitive Edition)
Chapter 21, Page 196

“Cortana initialized the Covenant file-duplication software. It moved and the entire thing pulsed and reached for her; she immediately shut down all contact with her translation suite.
The dark functions touched her code, wrapped around them, pushed against the barriers she had erected.
It happened too fast, but she didn’t stop the process. It was far too interesting to stop.
She distantly felt that portion of her mind blur and replicate, assembled line by line into its new location within Ascendant Justice.”

Halo: First Strike (Definitive Edition)
Chapter 31, Page 290

“Covenant icons entered the stream of symbols flowing along the surface of her holographic body. 'I discovered a file-duplication algorithm in the Covenant AI on Ascendant Justice. I successfully used it to reproduce my language-translation routines. I might use it to copy portions of my infiltration programming into the memory-processing matrix in the Master Chief’s MJOLNIR armor. t won’t be a full copy - there are replication errors and other side effects - but it would give the Spartan team access to some of my capabilities. Enough, I think, to get them through the Covenant security barriers.”

Halo: First Strike (Definitive Edition)
Chapter 36, Page 399

“I’ve reviewed your mission logs. Maybe it was the additional copying that caused its breakdown, but that copy did have some of my core personality programming as well. I just hope it’s not a sign of… some other instability.”

I do believe the Cortana in Halo 5 is nothing more than a rampant spike which she duplicated in Halo 4. When Cortana experienced rampant moments in Halo 4, she would paraphrase what the Gravemind told her in during their conversation between Halo 2 and 3. He is the one who brought her to the brink of rampancy and forced these ideas down her throat. Now in Halo 5 she’s shown believing them. IMO, it’s because she’s a rampant spike unknowingly suffering from the Logic Plague, just as the Ur-Didact was in Halo 4.

I firmly believe the Cortana is Halo 5 is a rampant fragment, but mutated and developed to act as if it is a complete duplicate.

I believe that in Halo 5 she’s the real Cortana

> 2533274793749599;2:
> Cortana does make copies of herself. She learned how to do this in Halo: First Strike.
>
> Halo: First Strike (Definitive Edition)
> Chapter 21, Page 196
>
> “Cortana initialized the Covenant file-duplication software. It moved and the entire thing pulsed and reached for her; she immediately shut down all contact with her translation suite.
> The dark functions touched her code, wrapped around them, pushed against the barriers she had erected.
> It happened too fast, but she didn’t stop the process. It was far too interesting to stop.
> She distantly felt that portion of her mind blur and replicate, assembled line by line into its new location within Ascendant Justice.”
>
> Halo: First Strike (Definitive Edition)
> Chapter 31, Page 290
>
> “Covenant icons entered the stream of symbols flowing along the surface of her holographic body. 'I discovered a file-duplication algorithm in the Covenant AI on Ascendant Justice. I successfully used it to reproduce my language-translation routines. I might use it to copy portions of my infiltration programming into the memory-processing matrix in the Master Chief’s MJOLNIR armor. t won’t be a full copy - there are replication errors and other side effects - but it would give the Spartan team access to some of my capabilities. Enough, I think, to get them through the Covenant security barriers.”
>
> Halo: First Strike (Definitive Edition)
> Chapter 36, Page 399
>
> “I’ve reviewed your mission logs. Maybe it was the additional copying that caused its breakdown, but that copy did have some of my core personality programming as well. I just hope it’s not a sign of… some other instability.”
>
> I do believe the Cortana in Halo 5 is nothing more than a rampant spike which she duplicated in Halo 4. When Cortana experienced rampant moments in Halo 4, she would paraphrase what the Gravemind told her in during their conversation between Halo 2 and 3. He is the one who brought her to the brink of rampancy and forced these ideas down her throat. Now in Halo 5 she’s shown believing them. IMO, it’s because she’s a rampant spike unknowingly suffering from the Logic Plague, just as the Ur-Didact was in Halo 4.

I almost forgot about this part, thanks for reminding me. No everything makes a bit more Sense to me…

for those who think this cortana is a rampant fragment

> 2533274817408735;1:
> At the end of Halo 4, in the final level, Cortana seemingly makes copies of herself in order to lower the Didact’s shield around the Composer so Chief can get in there to denote the Havoc nuke. But what I think is that, instead of copies, those were actually fragments. I say fragments because in her ending speech with the Chief, she said “Most of me is down there. I only held enough back to get you off the ship.” Furthermore, we know from the extended universe that during the events of Halo Reach, the Cortana given to Noble 6 was a Cortana that was managing the Forerunner tech under Sword Base, that was reunited with the Cortana on the Pillar of Autumn after Noble 6 delivered her to Keyes.
> So what I’m wondering is two things. 1) Is Cortana copying herself outright, or fragmenting herself in these cases? I feel like complete copies would be a bit OP and confusing; she could copy herself as many times as she wanted to exponentially increase her processing power. And would the copies be permanent? How would a complete copy know it was a copy and not the original? I want to believe that she instead fragments herself, creating partitions. I mean, otherwise, if it were a copying ability then there is no reason why the instance of her that saved John off the Mantle’s Approach couldn’t have stayed with him. 2) Assuming that only a fragment or incomplete copy made it through slipspace to the Domain, how much of her can we assume made the journey? I expect that this may be answered in the next Halo, but I’m wondering if any lore experts have any insight now.
> I know the Halo wikis state her power is “cloning” herself, but again I feel like there are issues that come up with being able to make full clones as opposed to partitions. But since I don’t know for sure, I want to pose this question to the community.

> 2533274931864540;5:
> > 2533274793749599;2:
> > Cortana does make copies of herself. She learned how to do this in Halo: First Strike.
> >
> > Halo: First Strike (Definitive Edition)
> > Chapter 21, Page 196
> >
> > “Cortana initialized the Covenant file-duplication software. It moved and the entire thing pulsed and reached for her; she immediately shut down all contact with her translation suite.
> > The dark functions touched her code, wrapped around them, pushed against the barriers she had erected.
> > It happened too fast, but she didn’t stop the process. It was far too interesting to stop.
> > She distantly felt that portion of her mind blur and replicate, assembled line by line into its new location within Ascendant Justice.”
> >
> > Halo: First Strike (Definitive Edition)
> > Chapter 31, Page 290
> >
> > “Covenant icons entered the stream of symbols flowing along the surface of her holographic body. 'I discovered a file-duplication algorithm in the Covenant AI on Ascendant Justice. I successfully used it to reproduce my language-translation routines. I might use it to copy portions of my infiltration programming into the memory-processing matrix in the Master Chief’s MJOLNIR armor. t won’t be a full copy - there are replication errors and other side effects - but it would give the Spartan team access to some of my capabilities. Enough, I think, to get them through the Covenant security barriers.”
> >
> > Halo: First Strike (Definitive Edition)
> > Chapter 36, Page 399
> >
> > “I’ve reviewed your mission logs. Maybe it was the additional copying that caused its breakdown, but that copy did have some of my core personality programming as well. I just hope it’s not a sign of… some other instability.”
> >
> > I do believe the Cortana in Halo 5 is nothing more than a rampant spike which she duplicated in Halo 4. When Cortana experienced rampant moments in Halo 4, she would paraphrase what the Gravemind told her in during their conversation between Halo 2 and 3. He is the one who brought her to the brink of rampancy and forced these ideas down her throat. Now in Halo 5 she’s shown believing them. IMO, it’s because she’s a rampant spike unknowingly suffering from the Logic Plague, just as the Ur-Didact was in Halo 4.
>
> I almost forgot about this part, thanks for reminding me. No everything makes a bit more Sense to me…

So, I really think that the cortana in halo 5 is a piece or fragment of the full Cortana, I also think there’s a fragment of Cortana that has apart of an unlocked gene that dr halsey gave her from the Librarian. Watch this. Also I think we will meet a Cortana that is cured from rampancy by the Librarian, in Halo 6 (Infinite).

PS: I’m still working on the Lore behind this

My theory was that the clones Cortana created on Mantle’s Approach were not independent entities that could survive on their own. Cortana being an AI is comparable to a program, such as a game, on your computer. You can start up a program on your computer via a shortcut, but if you delete the program’s master file, the shortcuts no longer work and the computer prompts you to delete them. Therefore, I believed that Cortana was the master file for her clones, and after she gave her life to save the Chief from the Didact, her death was basically equivalent to the deletion of her program’s master file, and thus her copies should have died right along with her, instead of just being stuck on the ship as 343i put it. It makes even more sense when you consider how Cortana’s rampancy affected her ability to perform at full capacity. We saw it multiple times throughout Halo 4’s campaign, therefore her copies should have had even less strength to survive independently.