OBTAINING ENZYME 42
When Ryley reaches the Disease Research Facility and enters Level 4 infection (“Infection has spread to the skin and pulmonary system,” or Architect Stage 2 “Green skin lesions and flu-like symptoms”), our partner advances to the next stage of “Unpredictable alterations to biological structure”. In other words, Aurelia is at the stage in which the Kharaa alters DNA, which is going to be our key for obtaining a source of Enzyme 42.

With the Sea Emperor calling us deeper, we make it to the Primary Containment Facility with our unconscious partner, and the plot proceeds as usual. Following the instructions of the Sea Emperor, Ryley leaves his partner in the aquarium and we go off to find the hatching enzymes.

What would happen if the alien bacteria that’s hijacking our DNA started dying before completing the process? We’ve left Aurelia in the presence of the Sea Emperor and her weakened Enzyme 42, which partially neutralizes the Kharaa infection. As the bacteria are killed midway through their DNA editing process, the genetic gaps that the Kharaa induced for its own propagation are replaced with the genetic code responsible for Enzyme 42 production. This resolves a major issue—Enzyme 42 is now available in her bloodstream. Now, Aurelia can serve as our Enzyme 42 wellspring later in the plot.

The children are hatched, the concentrated enzyme fully cures Ryley and Aurelia—all is well. Though we don’t know much about Ryley, we do know he needs to return home. However, our part-leviathan engineer and resident AI heir-turned-ecologist do not. Ryley departs for Alterra, the Sea Emperor dies, and Aurelia and BartAI remain, watching over her children and continuing their research on the ecosystem and Architect technology.


MOVING ENZYME 42 TO SECTOR ZERO
BartAI’s rudimentary storage medium is beginning to fail—it was never intended for such “primitive” use. Even after fully characterizing the Architect technology in the Crater, Aurelia is no closer to a solution. Long-range scans of 4546B for ionic energy signatures indicate the other hub of Architect activity is in the arctic. With BartAI in hibernation, our engineer modifies the Neptune rocket and heads off to Sector Zero, where she will eventually encounter 1) Al-An’s Sanctuary Zero and 2) Marguerit.


THE TIME BETWEEN GAMES
Enzyme 42 is now in Sector Zero; with this point resolved, the time between games can be interpreted creatively. Here’s what I imagine.

Our engineer meets and recognizes Marguerit from BartAI’s logs and stories. She uses this to establish trust and explain the situation. Aurelia provides Marguerit with ionic power cells and other hybrid Architect technology, which later will help Marguerit remain undetected by Alterra when they enter Sector Zero. If Marguerit still has lingering side effects of the Kharaa infection (if she wasn’t fully cured by consuming the Reaper leviathan), Aurelia provides her with her blood, which now contains the golden, highly concentrated Enzyme 42.

Aurelia discovers Sanctuary Zero through her scans for Architect technology, and in investigating the storage unit (looking to repair BartAI), “wakes” Al-An. We know from the Sanctuaries that the uploaded “souls” are conscious, but Aurelia activating the facility would explain why Al-An is able to scan the surrounding environment, broadcast signals, and communicate. It could also contribute to the failing power of Sanctuary Zero, as these additional abilities drain the power.

Luckily for Al-An, our engineer was with Ryley in the Primary Containment Facility and has plenty of ion cubes to fuel the Sanctuary for now. This also means there is no immediate urgency for an alternative storage medium. The two make an agreement that Aurelia will search for the components to forge his body, and Al-An will assist with repairing BartAI (Al-An does not advise putting him in an Architect body, because they are “not built to sustain beings with such primitive neural networks”).

Over the months that follow, Aurelia searches for clues toward body fabrication and visits Sanctuary Zero to discuss with Al-An. As the two form an unlikely friendship, Al-An confesses his role in the planetary Kharaa outbreak, which prompts Aurelia to tell him about the events in the Crater, the planetary cure, and her possession of Enzyme 42. There’s an interaction I loved between preRobin and preAl-An that went something like this (it’s been a while, so I don’t remember the exact words):

preRobin: The Sea Emperor was willing to give us the enzyme. Why didn’t you just listen?

preAl-An: We did not know to listen. We knew how to extract. And we did not want to die.

How can you blame them for that? Aurelia doesn’t, or if she does, Al-An’s punishment of slowly hearing his network die out while remaining conscious seems to have been enough for her. Now that both of them have discussed the truth, their agreement is revised such that after Al-An’s body is manufactured and BartAI is repaired, they will work together on tracking down the Architect network now that they have access to the Enzyme 42 cure.

ALTERRA ENTERS SECTOR ZERO
Alas, things are going too well. Just as Aurelia has found a lead on the Fabricator Caverns, her scans pick up an Alterra ship that has phased into nearby space. Time is short, and she is wary of Alterra’s intentions with the Architect technology. She warns Marguerit and Al-An before going to hide and deactivate the Architect remnants she has discovered so far.

During BZ, we find a rich plot of Alterra employee interactions which there is no reason to change. Instead, Alterra’s darker activities will be hidden from most staff on site. The main modification for Enzyme purposes is changing Outpost Zero to Research Station Zero, which is staffed by Lillian Bench and two additional supporting characters:
1. Dr. Jefferys LastName, Head of Xenobiology. The person in charge of Research Station Zero, Lillian’s boss, and our antagonist. His placeholder name is from preRobin’s research partner in the Early Access game.
2. Dr. Jillian LastName, Junior Xenobiologist. Co-worker of Lillian who is handling the darker side of Alterra’s activities under Jefferys. It could be implied that she does not survive the events pre-BZ due to her guilty conscience. This could be mentioned in Lillian’s memo to Robin as part of the reason she suspects that there is something more to Sam’s death.

Since Aurelia has worked with Alterra technology before, she would know their protocol, including the typical environmental scans they perform. However, the junior xenobiologist mistakenly uses a different wavelength. Imagine a PDA of Jefferys rebuking Jill until noticing that something actually came up on her scan.

Unfortunately for our part-leviathan engineer, she is caught, identified as one of the MIA Aurora passengers, and discovered to be a genetically modified human. The last point, according to Jefferys, changes her rights from the “survivor” to “research subject” category. Aurelia is imprisoned and interrogated about Architect technology. She refuses to unlock her encrypted PDA.

Meanwhile, Al-An is concerned. Sanctuary Zero is steadily losing power. Using the human SOS pattern taught by Aurelia, he signals for assistance to garner her attention. Instead, he receives Lillian’s; upon realizing it is Alterra tracking him, he cuts the broadcast (PDA in Lillian’s lab). Aurelia is interrogated about the broadcast, but does not reveal Al-An; however, she believes the sudden cut of power was the shutdown of the Sanctuary, and privately mourns for his “death”.

When the frozen leviathan is discovered, Alterra decides to experiment with the Kharaa in the Omega Lab because they have Aurelia in their custody producing Enzyme 42. Jefferys uses the pretext of extracting Enzyme 42 to use more forceful interrogation methods in the high security basement labs of Research Station Zero. He finds that Aurelia’s Enzyme production increases when under life-threatening conditions, and exploits that such that the Sea Emperor’s DNA expression is prioritized more and more. Construction of a new Enzyme 42 extraction lab begins adjacent to the frozen leviathan in the Phi Excavation Site.

Sam’s intervention (discussed later) causes Alterra’s swift exodus from the planet, leaving behind their equipment and research materials. Al-An’s sanctuary is in critical condition, and he is forced to activate the signal, no matter who may answer.


BASELINE BELOW ZERO PLOT
Enter our favorite xenobiologist, Robin, here to find the truth. Her first interaction with Al-An does not go well--he identifies her as Alterran, and associates Alterra with Aurelia’s disappearance (insert the original “Die Peacefully” Al-An dialogue from Early Access). He’s transferred into her body, Sanctuary Zero is destroyed, and after heated discussion, Robin clarifies her mission and agrees to build his body as usual.

Again as usual, you meet Marguerit on Delta Island and receive the same warm welcome. Al-An suspects her identity as Marguerit Maida from Aurelia, but does not divulge this to Robin. Robin tracks Marguerit down to her Seabase, meets Preston, and is sent off to deactivate the tracking tower, as usual. This time, however, when the tower is deactivated, Al-An tells Robin about a strange energy signal coming from the North, and a gold/yellow beacon is placed to indicate Research Station Zero.

If at any time Robin explores the Glacial Basin, she will not be able to access the Phi Excavation Site (containing the frozen leviathan and the new Enzyme 42 extraction lab) because of a high-tech Alterran encryption lock installed by the staff investigating the incident. This pushes the resolution of Sam’s plotline further into the story. Also, now that Research Station Zero is a full xenobiologist lab instead of an outpost, Sam does not spend her end days here, but instead is isolated in the Glacial Basin. As such, Sam’s quarter’s in the lab may be replaced by junior xenobiologist Jillian’s.


SECURING ENZYME 42 IN BELOW ZERO
Following the beacon to Research Station Zero, Robin finds Lillian’s typical PDAs (note that Lillian is not involved with Enzyme 42 extraction; Jefferys has her completely focused on Architect technology), and three other types: PDAs of Jefferys discussing with Emmanuel the value of the “high security, top secret security clearance” research subject; PDAs of Jefferys granting Jill high security clearance and access to the specimen, easily crushing her objections to the harsh treatments; and PDAs of Lillian asking Jillian why she’s acting strangely.

Upon opening the maximum-security door to the basement levels, your Xenoworx PDA alerts you to faint life signs below and attributes them to a genetically modified human being. To Robin’s even greater surprise, Al-An reacts to this message and encourages Robin to investigate. We find a few more disturbing PDAs that illustrate Alterra sacrificing morality for profit, and then we find our poor engineer.

She’s in rough shape and unconscious. How did she survive for this long after Alterra left? We can attribute the hyper-expression of the Sea Emperor’s genetics to her increased durability and regeneration ability. Robin needs to find a way to free her.

Robin investigates the disturbing research rooms and messes with the room controls, ultimately releasing the locks on the Architect equipment. She returns to the containment room and finds Aurelia’s PDA, which is locked. However, the PDA reacts to the unknown user and identifies her as Alterra personnel. Poor Robin can’t catch a break—with this revelation, our part-leviathan engineer attacks her by communicating with the unlocked Architect equipment, freeing herself in the process. An Architect energy blade stops at Robin’s throat—because of the Sea Emperor’s influence, wild-Aurelia can “see” Al-An like the Sea Monkeys can, enough to recognize her friend. She withdraws and escapes the facility.

Al-An and Robin interact similarly to when Marguerit threatened Robin on Delta Island, but the roles are reversed: Robin thinks the gold-streaked nonhuman is dangerous, and AL-AN insists that she is an ally. Because she didn’t carry Alterran equipment, you have no follow-up beacon. Robin leaves with her PDA.

If you visit Marguerit during this time, Robin’s description and the disturbing PDA logs prompt her to identify the wild attacker as Aurelia LastName, a good kid who “ain’t in her right mind”. She instructs Robin to call her immediately if you encounter her again. When Robin asks how Margerit would subdue her, she says that she can make enough tranquilizer to take down a leviathan. On that note, Robin departs and continues her exploration.

CAPTURING THE ENGINEER
While exploring the Purple Vents biome, Robin will encounter a stream of golden Enzyme 42, such as the one left behind Peepers in the first game. Following this deeper into the Crystal Caves will lead to the Fabricator Caverns, initiating a cutscene in which Robin is attacked by a Shadow Leviathan, which is repelled by the gold energy field of wild-Aurelia, who indicates the entrance of the Fabricator Base while fending off the leviathan.
Robin and Al-An investigate the Fabricator Base, and make note of the components required to fabricate his body.

Now that this base has been found, Al-An will begin to indicate body component beacons as time progresses. When you exit the Base, the leviathan is nowhere in sight. Robin calls Marguerit and follows the golden bloodstream back up to the Purple Vents. There you have another cutscene in which you find wild-Aurelia, who approaches you. Enter Marguerit’s PRAWN suit, which distracts the part-leviathan long enough for Marguerit to attack and subdue her. With this, Marguerit tells Robin she’s taking Aurelia “out of this damn water” and to find them at her greenhouse, which now has a larger structure.


REHABILITATION AND BONDING WITH MARGUERIT
When rehabilitating Aurelia, Robin has the opportunity to bond with Marguerit. This can be achieved through hunting predatory animals and completing fetch quests. Once enough in-game time has passed, Aurelia’s gene expression returns to normal and she regains her senses, allowing her to interact with Robin when she visits.

Before Robin interacts with Aurelia, Al-An will ask her to keep his presence a secret. Because our engineer is in very poor condition, he does not want her to focus on anything other than recovery. However, Aurelia is already aware of Al-An’s presence in Robin’s body due to the influence of the Sea Emperor. Because Robin does not mention it, she believes Al-An has reasons to hide his presence and will not press for details. While this misunderstanding is in place, Robin will be unable to discuss Al-An with Aurelia.

Aurelia will again serve the role of creating hybrid schematics from Robin’s scans of Architect Artifacts. Theoretically, if Aurelia was a highly-ranked member of the organization focused on preserving ecological planetary systems, Robin as a xenobiologist may have encountered her work previously, which would give her a baseline to connect with the bioengineer.


FOLLOWING SAM’S FOOTSTEPS
Each time Robin visits the Greenhouse in a new game day, she can interact with either Marguerit and Aurelia with new dialogue. If Robin has found the encryption lock in the Glacial Basin, she can discuss it with the two of them. Marguerit will state that Aurelia isn’t well enough to make the trip across Sector Zero and return, and instructs Robin to build a Land Base in the Glacial Basin. There are no location restraints, but to fulfill the mission, the Land Base must have at least one Large Room, one Multipurpose Room, and one Observatory (which Marguerit will convert into a greenhouse). Once this is completed, Marguerit and Aurelia will move to the Glacial Basin Land Base for the rest of the game. Constructing Aurelia’s workbench will allow her to synthesize blueprints for you.

Once in the Glacial Basin, Robin can recruit Aurelia (using Architect prosthetics) to unlock the road to the frozen leviathan at the Phi Excavation Site. The three (including Al-An) progress to find the Enzyme 42 extraction facility and the leviathan itself. Aurelia remains in the facility while Robin investigates.

Let’s talk about Sam’s plan. Sam knows about the frozen leviathan and that the Omega Lab is mutating the Kharaa bacterium, so the Enzyme 42 that the xenobiologists have mysteriously procured may even not work as a cure. To prevent disaster, she resolves to stop Alterra’s research.

She has heard a rumor from Lillian that the Enzyme 42 extraction site is located in the caves with the frozen leviathan. While investigating, she meets Marguerit, and earns her trust. The two develop a plan: Marguerit will steal a Seatruck and destroy the mutated Kharaa in the Omega Lab, and Sam will cut off Alterra’s access to the frozen leviathan.
To do this, Sam plans to sneak into the Phi Excavation Site at night and use her Spy Penglings to detonate charges at each of the cavern entrances, such that it is cut off from the rest of the Glacial Basin. The explosions would destroy the Spy Penglings, erasing the evidence of her sabotage. Once she is trapped inside the caverns, she would use her biochemical knowledge and the Enzyme 42 extraction facility to cure the leviathan and eliminate the Kharaa bacterium altogether. Once Alterra excavates a way through the ice, they would find her and the cured leviathan, but not enough evidence to pin her as the culprit. (Sam has no way of knowing about the true source of Enzyme 42, and that Aurelia has not been moved from Research Station Zero to the new extraction facility yet. Sadly, her plan would have failed anyway.)

She uses the Spy Penglings to hide resources in the caverns for her to survive on in the coming weeks. On the day of her death, she records her final message for Robin. Once the researchers have left for the day, Sam infiltrates the frozen leviathan caverns and begins deploying her explosive Spy Penglings. However, Parvan had been recently reassigned from overseeing the Koppa Mining Site to Security in preparation for the Enzyme 42 research subject’s transfer into the Phi Excavation Site. Parvan begins to patrol in the danger zone of the blast, and Sam goes to intervene. But Parvan sets off the Spy Pengling, killing him and destabilizing the area. Sam dies from a fall once again. The remaining Penglings detonate, and the Phi Excavation site is destabilized.

Alterra investigates the Phi Excavation site and rules the deaths there as negligence. However, Marguerit, who has not heard from Sam, completes her piece of the plan and attacks the Omega Lab.

Alterra is forced to withdraw immediately following news that the Omega Lab has been compromised, potentially releasing mutant Kharaa into the environment. [Another contributing factor may be that Jillian (Lil’s coworker) has tipped off the organization to which Aurelia belongs that she is in Alterra custody. If they conduct an investigation, Alterra’s violations would be revealed.] Washing their hands of 4546B, Alterra withdraws permanently.


CURING THE FROZEN LEVIATHAN
Robin discovers the truth from the PDAs around the excavation site. She resolves to cure the leviathan in her sister’s stead, and Aurelia agrees to assist her. The bioengineer warns Robin that to fully cure the leviathan, they will have to forcibly circulate Enzyme 42 through its bloodstream, which could have unpredictable consequences.

Robin discovers that Sam, being a brilliant roboticist, designed a specialized pump for this purpose. We get to see Sam's talent shine in a complex schematic. Robin sets off to gather the materials required to manufacture the pump mechanism, sensors/controls, and energy source. Meanwhile, Aurelia begins the painful process of extracting Enzyme 42 using Alterra’s equipment. If Al-An asks you to interact with her during this period, Robin will express concern to her; however, Aurelia will remark that this type of extraction is what the Architects intended to perform on the Sea Emperor’s newborn children. Al-An will react and express regret to Robin, who now suspects that Aurelia is aware of Al-An’s presence (combined with Aurelia guiding them to the Fabricator Caverns).

After assembling the pump framework, Aurelia will provide Robin with enough Enzyme 42 to treat the surface lesions on the leviathan’s skin, so they can test if it is effective against the frozen Kharaa variant. Robin does this successfully, and then can manufacture the pump control board and energy supply.

The pump will require massive amounts of energy to precisely move the frozen blood. Robin has to set off for an ionic energy source. Once she returns, she loads the Enzyme from Aurelia and activates the pump. Soon, your PDA is unable to detect any traces of the Kharaa bacterium. Aurelia and Robin depart.

Once the three of you have made it some distance away, Robin tells Aurelia (and Al-An) her monologue about closure and fulfilling her sister’s legacy. Soon, there’s a cracking sound through the ice. A cutscene is triggered in which the frozen leviathan breaks free, its heart having been restarted, and retreats to the land in the West beyond the Glacial Basin. Unpredictable effects, indeed. After this happens, you can no longer access the Phi Excavation Site--it has been destroyed.

REUNITE AURELIA AND AL-AN
After completing Sam’s story path, Robin can choose to confront Aurelia by asking if she knew that Al-An was inside of her all along. She will admit this, and Robin can facilitate communication between her and Al-An to resolve the misunderstanding. Going forward, Robin can ask Aurelia more detailed questions about hybrid technology and the locations of the body components. Robin can also facilitate Al-Ans interactions with Aurelia; I can imagine Al-An saying something matter-of-factly and Robin translating a more amusing version.

REPAIR BART.AI
At this point, Aurelia will ask for your and Al-An’s help with repairing the vessel that holds Bart Torgal’s consciousness. Al-An will point out a new Artefact that may be useful, but in a treacherous area. Once found and scanned, Aurelia will fix the vessel, and BartAI 2.0 may accompany you in the Land Base or in your Seatruck.


CHARACTER BONDING
What’s left? Your character has yet to explore and discover all of Al-An’s body components (which could be more than three if the plot were to be extended). In the meantime, Robin can deepen her relationships with the characters she’s met.

Al-An: In the audio files for the released game, there are so many cut conversations between Robin and Al-An about the nature of Architects and their homeworld. Robin can bond with Al-An through these discussions, and by discussing Architects with Aurelia and BartAI—Al-An providing input at times. Scanning all of the Architect Artefacts, includes the neural interface for BartAI, deepens the connection further. Robin and Al-An become true friends.

Marguerit: Robin deepens her bond with Marguerit by following her quests during the storyline (deactivating the surveillance tower, rescuing Aurelia, building the Land Base, fixing BartAI). New dialogue can be unlocked by completing additional quests: 1) sparring with Marguerit, 2) completing hunting challenges, and 3) killing a leviathan (probably the Ice Worm, since the NPC characters will be inhabiting the Land Base of the Glacial Basin). Completing these unlocks new dialogue, and it becomes obvious that she cares for Robin and the others in her own way.

Aurelia: Robin and Aurelia establish a deeper bond when following Sam’s footsteps. Robin confides her worries about what she will find out about her sister, and Aurelia supports her. Later, once Sam’s pathway is completed and the misunderstanding with Al-An is resolved, Robin can talk about her excursions in Sector Zero with Al-An, which Aurelia enjoys hearing while she is stuck recovering in the Land Base. Our engineer becomes a sister-type character, someone Robin can confide in who isn’t as detached as Al-An or gruff as Marguerit. We get more human perspective from Robin.

BartAI: You are two curious xenobiologists on an alien planet—a perfect match for fast friendship. BartAI has adjusted to being digital and uses camera drones to explore the ocean. Robin can discuss xenobiology with BartAI based on the organisms she has scanned. BartAI may request she scan deep sea organisms that are outside of his access range. Together, the two of you can synthesize “Advanced Theories” regarding the function of the Sector Zero ecosystem. Depending on the organisms you have scanned, BartAI can work with Aurelia to produce schematics of biological tools, such as an electrical repellant weapon based on the attack of the squidshark. He provides the xenobiologist outlet that allows Robin's passion to shine.


THE FINALE
Before we get to the ending I have in mind, let’s discuss the possibility of multiple endings.


BAD ENDING 1: Alterran Scum
You attack Marguerit before deactivating the tracking tower. She kills you in self-defense.
If you attack Marguerit after establishing trust by deactivating the tracking tower, she will take it as sparring. You’ll obviously lose, but she won’t kill you.


BAD ENDING 2: Old Scars, New Wounds
You investigate Research Station Zero without Al-An. With nothing to bring her back to her senses, Aurelia kills you when Robin is identified as an Alterran employee.


BAD ENDING 3: Alone in the Ice
You rescue Al-An and build his body without having rescued Aurelia. Because of this, your relationship with Al-An does not deepen, and you are unable to resolve Sam’s plotline (you can’t access the frozen leviathan and you lack Enzyme 42). After constructing Al-An’s body, he thanks you, and that is all; he then removes Robin’s memories of him and leaves the planet. Robin wakes up alone in the Glacial Basin, no closer to the truth than before.


NORMAL ENDINGS: Farewell OR New Adventures
You rescue Al-An and Aurelia, and complete Sam’s legacy. You have connections now with Al-An, Marguerit, and Aurelia, but do not deepen your relationships with the characters further (i.e. you don’t resolve the misunderstanding between Aurelia and Al-An, you don’t bond further with Marguerit, and you don’t repair BartAI.). Because of this, Robin is the only one aware of Al-An’s current situation; Robin never tells Marguerit about the alien, and though Aurelia knows, due to their misunderstanding, she does not pry. When Robin constructs Al-An’s body, she has the option to go with him through the phase gate or stay on 4546B.

If you choose to stay, Al-An will thank you for everything you’ve done and will leave the planet with Robin’s encouragement to stay hopeful. You part ways at the gate behind Research Station Zero, which deactivates after he passes through. When you return to Marguerit and Aurelia, the latter notices that Al-An is gone, and greets you sadly. You look out to a new sunrise on 4546B.

If you choose to leave with Al-An, you can return to the Land Base in the Glacial Bay and say goodbye to Marguerit and Aurelia. Though Robin doesn’t provide enough details, Marguerit understands that you are leaving the Sector and gives you some supplies, scolding you for departing so suddenly. Aurelia, who can see that Al-An is no longer inside Robin, grasps the situation, and gives her vials of Enzyme 42. Robin can now leave the planet with Al-An as in the released game, but has closure with those left behind and is prepared to face the future (with Enzyme 42).

TRUE ENDING: New Harmonies
This is the ending that pushed me to write all of this text. To achieve this ending, you must:

- Rescue Al-An (obviously) and build his body at the end of the game
- Rescue Aurelia and then help Marguerite rehabilitate her
- Assist Marguerit procuring resources and complete Marguerit’s leviathan hunt
- Complete Sam’s storyline with Aurelia after she unlocks the passage to the frozen leviathan (Find out Sam’s true plan, Assemble Sam's last design: the leviathan pump, Cure the frozen leviathan)
- Resolve the misunderstanding between Al-An and Aurelia
- Unlock all hybrid human-Architect technology by scanning all Artifacts
- Repair BartAI with Al-An’s assistance
- Scan all organisms in Sector Zero to complete your and BartAI’s xenobiologist research

If you’ve fulfilled all of these conditions, you will have maximized your relationships with all of the characters. You will be prompted by Al-An that everything is ready for body fabrication. When the player is ready, Robin will call together Aurelia, Marguerit, and BartAI at the Land Base and tell them all the full story about Al-An, and that she plans to go to the Fabricator Caverns. All of them resolve to accompany you to protect you from the Shadow Leviathans.

Marguerit distracts one leviathan in her Prawn suit, while Aurelia and BartAI use Architect technology to repel the other. This is the only time you can access the Fabricator Caverns with their assistance.

Once you fabricate Al-An’s body, he will thank Robin and discuss his plan for the future. Robin wants to come with him to the Architect homeworld. The two of you will exit the facility to repel the Shadow Leviathans. Using Architect tethering, you're all returned to outside the Land Base.

While Marguerit and BartAI celebrate their survival with Robin, Aurelia and Al-An have a brief discussion before Al-An greets the group and informs Robin to find him at the gate behind Research Facility Zero. Robin expresses her intention to depart to the group, and to her surprise, all of them are packed and ready to depart because Aurelia anticipated their leaving. “Did you think we’d let you go at it alone, kid?” Aurelia tells Robin that Al-An has no objections. Robin, Marguerit, Aurelia, and BartAI meet Al-An behind Research Facility Zero, and together move the energy pillars.
You depart 4546B. You have:
• Discovered the truth about the death of your sister
• Cured the frozen leviathan, and thus eradicated Kharaa from the entire planet
• Saved three souls (Al-An, BartAI, and Aurelia) who would not have survived without your intervention—and arguably Marguerit by giving her a reason to keep fighting
• Secured a source of Enzyme 42, the only known Kharaa cure, for future adventures

Al-AN has found a new--slightly discordant--harmony between the thorny fighter Marguerit, steadfast bioengineer Aurelia, the curious digital xenobiologist BartAI, and the driven truth-seeker Robin. Because of the part-leviathan's existence, he has access to Enzyme 42 and is thus able to bring the cure back to the Architect homeworld. Robin came to 4546B alone and leaves with a new makeshift family. At the very end, deeper meaning echoes in the last line: “With you, I am ready to face whatever awaits.”

Cue Subnautica 3.

If you made it all this way, thank you. This was written with love and some lore research, but if I’ve overlooked something, let me know. What do you think of the true ending?

Man that's a record wall of text just there. Most of us are just goldfish and are stuck in a loop re-reading the opening paragraph.

Stopped reading at "comrades"

I had forgotten that I had also posted here. The updates to this reinterpretation are in this other thread:
https://steamhost.cn/steamcommunity_com/app/848450/discussions/0/5501743491371401799/

Just a thought, but making a substance that will 100% kill a disease-causing agent isn't really the challenge, where medical research is concerned. Making one that will kill the disease-causing agent *without harming or killing the patient* is what's tricky. Sam's task was vastly easier than Ryley's or the Architects', because the frozen leviathan wasn't going to get any deader even if she brewed up a concoction that was lethal to Kharaa and its hosts, alike. She didn't have to make a vaccine, just a disinfectant.

I like it! Very well done. I appreciate the way you largely kept the BZ storyline intact while adding enough detail to make it meaningful.

Perhaps some more development for Marguerit’s character. I’d think she’d secretly feel a bit guilty that, even though her instincts were right, she was responsible for killing Paul & Bart. So possibly that can be added as a reconciliation between Bart AI and her.