As the Union tries to normalize relations with the Krill, the Orville is allowed to explore the Neklav Sector — territory previously closed off due to long-term tensions. However, what the crew finds turns out to be new danger. Claire, meanwhile, has to deal with a figure from her past.
This episode provides examples of:
- Achilles' Heel: The microbes are able to transform any species into theirs, but the process happens so quickly that the transformed have non-existent immune systems (at least for a while) and can be killed by something as simple as the common cold.
- Amicable Exes: Claire is content to be this with Admiral Christie, even though he clearly wants to try and restart their relationship.
- All Myths Are True: The Krill view the Expanse as a cursed place full of demons that corrupt the living. Despite seeing it as a tall tale, Mercer points out that myths tend to be based on something in reality, and sure enough it is.
- Arbitrary Skepticism: Mercer, Kelly, and Admirals Halsey and Christie have a discussion about the Krill warning them of "demons" lurking within the expanse. Christie immediately dismisses the claim because of the source, while Mercer simply finds the "horror movie stuff" from the Krill's holy texts too outlandish. Kelly points out that while the Krill use flowery language and metaphor, their beliefs usually have some basis in reality. Halsey defies it, pointing out that if they were indeed in a horror film, he wouldn't walk into the Haunted House.
- Body Horror: Those exposed to the alien microbes have their DNA rewritten and their bodies painfully transformed into something more insectoid than mammalian. Christie transforms over the course of a day, while those he infects transform in under a minute.
- Chekhov's Gun: Early in the episode, Admiral Christie shows Claire his old wedding ring, and mentions that it’s made from a rare material, “Selayan sunstone”. Later, in sickbay, he asks Claire to bring him the ring, and she slips it on his finger. After he disappears, she locates him by having the ship’s scanner look for Selayan sunstone, and she distinguishes him from the others by the ring he still has on his finger.
- Cut the Juice: When his transformation overtakes his mind, the first thing Christie does is set up a dampening field that shuts down main power, blocks comms, and disables weapons. By the time LaMarr devises a workaround, he's already converted several members of the crew.
- Death of Personality: While the converted crewmembers are technically still alive, their minds and bodies are irreversibly altered, meaning that who they used to be is gone forever.
- Don't Make Me Destroy You: Claire uses this threat to drive the aliens off the Orville, having deduced they're vulnerable to disease so soon after transforming.
- Don't Touch It, You Idiot!: Claire politely warns Grayson that it's probably best not to touch anything on the organic station. Shame no one gave Christie that warning.
- Everyone Has Standards: The Krill aren't fond of other species, and it's been made clear by many of their officials that they have no interest in a long-term treaty with the Union. But when they learn that the Orville intends to travel into the Expanse, they are horrified at the thought of what might happen to them (believing that the area is full of soul-sucking demons), to the point that one of them even prays for their safety.
- Failsafe Failure: Subverted, to horrifying effect. It appears that in the event of a ship wide power outage, all the doors lock open, to prevent anyone from being trapped in a crisis. The flipside of this is that it allows the aliens total access to the ship.
- Forgot About His Powers: Since the alien infection is biological, it would've made perfect sense to send Isaac in to gather samples/information. Since he is not a biological being, he could not be infected. Somehow, no one thinks to do this.
- "I Know You're in There Somewhere" Fight: Claire uses this to get through to Christie, to convince him that she will destroy him and all the others if he doesn't leave peacefully. Though the alien insists it is no longer Christie, it also knows she isn't bluffing.
- Insectoid Aliens: Those transformed by the microbes gain insectoid features such as multiple eyes, an exoskeleton, and venom sacs.
- It Can Think: Though the aliens act like vicious monsters, the one that was Christie is smart enough to use the Admiral's command codes to shut down power, and can be reasoned with.
- Know When to Fold 'Em: The aliens are reluctant to stop attacking the crew because it's how they propagate their species, but Claire seriously threatening to kill all of them if they don't retreat convinces the leader to agree to her demands.
- Lampshade Hanging: When discussing the Krill's warnings about the Neklav Sector, which Mercer compares to "horror movie stuff," Admiral Halsey points out that you don't go into the haunted house in a horror movie. Later, when Mercer gives the order to proceed into the Kalarr Expanse, Gordon acknowledges the order with "Now entering the haunted house."
- Loss of Identity: People transformed into the aliens lose any semblance of their past selves, and are replaced by a single minded drive to assimilate others. It's suggested though, that enough of Admiral Christie's past personality is still in him that he's able to be reasoned with.
- Lured into a Trap: The alien space station sending out a distress signal is actually trying to lure in sentient species to be infected and converted into their own. Once it's caught some, it signals for a ship to approach and collect the new converts.
- Mauve Shirt: Defied in the case of Nurse Henry Park. A recurring character introduced back in season 1, he is presumed lost to the aliens.
- New Old Flame: Admiral Christie is Claire's ex-husband, though he was never once mentioned at any point in the first two seasons. It's implied that this is because Claire wanted to move on as far and fast as possible from the relationship. In fact, she had even stated in the first season's "Into the Fold" that she had "never found anybody suited to be her husband." The admiral, meanwhile, wants to try again.
- Nothing Is Scarier: The Kalarr Expanse is an inky black nothingness, without even any visible stars. It naturally unnerves the crew when they find it.
- O.O.C. Is Serious Business: When the Orville crew mention that they are looking to explore the Kalarr Expanse, the Krill show uncharacteristic concern for their safety, warning them that there are dangers there (phrased within the language of their religion) and that it is so horrible there that the normally fearless Krill will not venture into the area, not even to rescue them as part of the new treaty.
- Organic Technology: The aliens use advanced bio-technology to grow ships instead of building them.
- Realpolitik: The Krill delegation bluntly says that they are only in an alliance with Union because the Kaylon threat is greater, and intend to dissolve the alliance as soon as the threat has passed. In response, Admiral Christie says that he hopes the relationship will stay friendly after the threat has passed, instead of the two sides returning to warring against each other.
- Red and Black and Evil All Over: The first sign that the aliens are probably not the friendliest sort is their ominous black station with glowing orangish-red parts all over.
- Red Shirt: Other than Admiral Christie and Nurse Park, none of the infected crewmembers are characters we've met before, and only one is even named in the episode.
- Scream Discretion Shot: Played straight when Nurse Park comes face to face with an arachnid.
- Shout-Out: The notion of an expanse of space without any visible stars sounds a lot like the Void from the Star Trek: Voyager episode "Night", and Admiral Christie's transformation into a creepy insectoid alien seems to take a lot of cues from Lt. Barclay's metamorphosis into an equally hideous proto-arachnid in the seventh season TNG episode "Genesis". The notion of a viral method of procreation also brings to mind the season 4 TNG episode "Identity Crisis", as well as the virus-induced Plague Zombies from Lower Decks' premiere episode "Second Contact" and also "Favorite Son" from Voyager, which featured the Taresians trying to transform Harry Kim into one of them via a retrovirus.
- Stay in the Kitchen: Claire says her marriage to Admiral Christie fell apart because she wanted an equal partner but he wanted a bed warmer.
- Teacher/Student Romance: Claire and now-Admiral Christie began a relationship while she was still a student at Union Point and he was a professor. She says that they tried to spin a tale of a whirlwind romance that occurred after she graduated, but that they probably didn't fool anybody.
- That Man Is Dead: Claire tries to appeal to Christie in his alien form, only for the alien to snarl back that it is not him, but something more.
- Too Much Information: Christie quickly regrets asking Isaac about Claire's interests:Isaac: Her recreational interests include music, dancing, fine dining, rain showers, and sexual relations. Her preferred mating positions include...Christie: Whoa, that's plenty helpful, Isaac, thank you.
- Transformation at the Speed of Plot: Justified. Admiral Christie transforms over what is implied to be the course of a few hours, maybe half a day at most, while those infected by the aliens transform within seconds of exposure. It's reasoned that, compared to the small spray of microbes Christie was given, the thick stream of venom the aliens spit at their victims is a far more concentrated version that works much faster as a result.
- Uniformity Exception: When Claire confronts one of the aliens, she can tell it’s the transformed Christie by the wedding ring he’s still wearing on his finger.
- Viral Transformation: Indicated to be how the aliens naturally reproduce. They broadcast distress signals from a large space station, drawing unsupecting ships in, and then infect anyone who comes aboard with spores that rewrite their entire genetic code. Once one is completely transformed, they will proceed to hunt down, and spew a more concentrated version of the spores onto a victim, transforming them as well. One of the alien ships will then come, and collect the transformed crews. Claire compares the aliens, in this regard, to parasites, taken to extreme.
- We Will Meet Again: The alien that was Christie agrees to leave under the threat of extermination, but warns that they will come back some day.
- What Measure Is a Non-Human?: Members of the crew are transforming and attacking others. Ed wants to try to save them in the hopes that a cure can be found, but Claire insists that the genetic changes are so fundamental that the victims are no longer who they used to be and that wiping them out will be for the best. They compromise by giving them a chance to escape with the members of their species called by the station.
- The Worf Effect: Talla has some trouble fighting the alien creatures, which shows how much of a threat they are that even a Xeleyan has trouble putting them down. Downplayed, in that Talla is clearly quite stronger than they are and does win the fight, but their tenacity, their numbers, the danger of being infected by their venom spray, and the fact that they're mutated crew members that could theoretically be restored to normal keeps Talla from engaging as seriously as she might have otherwise. Even so, she still kills a few of them before she is able to disengage and take one to sickbay.
