Played by: Emma Stone
A feisty, unhappy young woman still reeling from the death of her younger sister. She participates in the Neberdine trial because of her addiction to the 'A' pills, hoping to steal more from the lab while there.
In the first 'B' scenario, she projects as Linda Marino, a nurse tasked with returning a rare lemur to its intended owner, and Arlie Kane, a con artist out to steal the missing chapter of Don Quixote at a seance. In the 'C' scenarios, she projects as Annia, an alcoholic elf ranger en route to deliver the princess to a magical lake, and Ruth, a CIA sleeper agent.
- Action Girl: Ruth. Over the course of her time on screen, she frees Owen from captivity, guns down several dozen "Inner Demons", and casually Waif Fus numerous others into submission.
- The Alcoholic: Annia spends most of her time getting completely hammered, and is only spurred into action when one of her attackers manages to destroy her flask by mistake.
- Badass in a Nice Suit: Ruth, who mows down several mooks while in a distinctive red suit.
- Berserk Button: Annia is hopeless in combat up until an arrow punctures her flask of booze, whereupon she charges headlong into battle with a scream of rage.
- Character Development: Gradually grows more inclined to trust Owen, eventually opening up and seizing opportunities to stay with the people she loves rather than shutting them out; comes to a head in the finale in which she not only reconciles with her sister's virtual self but also rescues Owen from a mental clinic.
- Classy Cat-Burglar: Arlie Kane poses as a slick society dame while secretly casing wealthy houses to rob, often sneaking around the mansion and shimmying up chandeliers while still in her fine eveningwear.
- Femme Fatale: Arlie in the second "B" story plays into the type, being a beautiful con artist who strings Ollie along in the hopes of stealing the missing chapter from him as soon as he acquires it.
- Functional Addict: Annie is addicted to the A pills, but has so far managed to keep herself relatively stable despite her ongoing attempts to avoid withdrawal; in fact, most of her problems are more due to depression than anything else.
- Genre Savvy: Annie breaks Owen out of the mental clinic using a method that she saw in a movie, so she knows it works.
- Going Cold Turkey: Her story begins with her running out of A pills and resolving to do without them from then on... only to hurry back to her dealer after she starts feeling the effects of withdrawal.
- Jerk with a Heart of Gold: Foul-tempered, unscrupulous and disagreeable though she may be, Annie is capable of surprising acts of compassion, even sounding a little ashamed of herself when she admits to lying to Owen in the aftermath of the A test.
- Manic Pixie Dream Girl: Linda in the first "B" scenario has shades of this; after their zany adventure, her relatively straight-laced husband tells her he loves her for how much excitement she brings into his life. Almost completely averted with the real Annie - while the reclusive Owen would be a classic MPDG target, Annie is a fleshed-out character with her own dramatic arc.
- Parting Words Regret: Annie's last two days with Ellie were spent hurting her feelings, apparently angry over her moving away. It was during their last argument that their car happened to stray over to the wrong side of the road, getting them hit by a truck in the process; Ellie didn't survive the collision, and it's clear that the guilt over their final interaction still haunts Annie to this day.
- Sour Outside, Sad Inside: Her outwardly aggressive personality hides a good deal of self-loathing and depression, and she has a habit of saying deliberately hurtful things in order to hide just how upset she really is. In one of her first moments of honest self reflection during the interview with Dr Muramoto, she openly admits that she doesn't feel as though she deserves to progress to the B test and doesn't deserve to be cured. Tellingly, following the B test she is formally diagnosed with Borderline Personality Disorder.
- Tsundere: Annie is often abrasive and argumentative, but can be surprisingly warm around loved ones, even bonding with Owen over time despite their initially standoffish relationship. Perhaps best illustrated when, after going out of her way to drive Ellie to tears the previous evening, Annie can be seen sleepily hugging her the following morning.
- You Are What You Hate: Despises her mother for being manipulative, abusive and frequently absent... and yet isn't above manipulating or hurting people in order to get what she wants. Her second "B" scenario brings this self-loathing tendency out in force in the form of the deceitful con-artist Arlie, who Annie later claims is exactly like her mother.
Played by: Jonah Hill
The youngest son of a prominent New York family being pressured to commit perjury for his brother Jed. He participates in the Neberdine partly due to possible schizophrenia but mostly due to being in serious need of money.
In the first 'B' scenario, he is Bruce Marino, Linda's straight-laced husband dragged into the lemur heist, while in the second 'B' scenario, he projects as Oliver Hightower, a slick gentleman thief and former partner-in-crime to Arlie. In the 'C' scenarios, he is Owen, the son of a mafia boss acting as a mole for the NYPD, and Snorri, an Icelandic government worker who has accidentally killed an alien.
- Angrish: Snorri Argnarsson, Owen's final character, begins losing his grip on coherent speech during his account of Ernie the Alien's death, reducing him to tearfully whimpering barely-audible gibberish into his microphone, then bawling incomprehensible answers at the top of his voice.
- Animal Motifs: Owen is often associated with hawks, having rescued one when he was younger; during the pre-trial testing session, he instantly associates an image of a hawk with the concept of justice; during one of the later scenarios, he actually transforms into a hawk in his attempts to find Annie; last but not least, an injured hawk is seen riding after him on a rogue cleaning robot during the final episode.
- Awful Wedded Life: Owen the gangster, after retiring from his life of crime to be with Olivia, soon finds himself stuck in the real Owen's one-room apartment with a ridiculous number of children and an increasingly temperamental wife. It gets so bad he jumps out the window to escape it all - only to accidentally realize who he is in the process.
- Beware the Silly Ones: Snorri is undoubtedly a ridiculous Funny Foreigner, but he's a lot more adept with a gun than you'd expect, managing to gun down several Inner Demons in quick succession while Ruth is distracted.
- Character Development: Goes from freezing under pressure from Jed to actively putting himself in harm's way to save Annie. Comes to a head when he gives up on defending Jed and throws him under the bus in court.
- Chekhov's Skill: Owen is in the habit of obsessively working on a Rubik's cube when anxious. In the final scenario, the machine that can unlock the lab doors in the real world comes equipped with a Rubik's cube, meaning that Owen is the only person who can operate it and give Mantleray a chance to stop Gertie.
- Driven to Suicide: At the end of his first C scenario, Owen jumps to his death from a window... only to find himself landing in a scale model and awakening from his persona in the process.
- Functional Addict: Albeit only in the crime fiction scenario, in which he requires pills from the family consigliere in order to sleep and continue his work as a police informant.
- Gentleman Thief: Oliver Hightower is a charming man skilled at sleight-of-hand, but is also a fairly notorious thief.
- Gosh Dang It to Heck!: Bruce Marino is very much a family man and - in stark contrast to Linda - refuses to use any expletive more serious than "fudge."
- Happily Married: As Bruce, to Linda; in sharp contrast to his relationships in other simulations, Owen's character finds himself very content with his wedded life in the first B scenario, even if it does sometimes put him unpredictable circumstances.
- No Good Deed Goes Unpunished: Refuses to protect Jed in court and allows him to go down for sexual assault; as a result, his family have him declared insane and packed off to a mental hospital.
- Shrinking Violet: Owen in a nutshell; quiet, lonely, lacking confidence, and often drowned out by people more self-assured than he is, he rarely ever speaks up for himself unless he's been badgered to the point of a breakdown. In what might be construed as a bit of subconscious wish-fulfillment, his characters in the various scenarios are far more outgoing - including a happily-married man, a gentleman thief, a gangster-turned-informant, a hawk, and an assistant diplomat dealing with a First Contact scenario. Dr Mantleray diagnoses him as suffering from "perpetual cowardice," among other things.Owen: What's wrong isn't that I'm sick... it's that I don't matter.
- Stress Vomit: Owen suffers one of these very early on; having been pushed to the very limits of his composure by being forced to testify at his brother's trial, running out of money and losing his job to a long-term furlough, another onset of hallucinations sends him sprinting for the nearest toilet.
- Tattooed Crook: In drug scenarios where Owen is a gangster, he sports tattoos.
- Try to Fit THAT on a Business Card!: Inverted. Owen's character in the final scenario, Snorri Agnarsson, is referred to as the Temporary Administrative Adjunct Assistant to the Consulate of Iceland, and the diplomat announcing him sounds exasperated just saying the title. However, it is meant to indicate limited importance, demonstrating just how far down the totem pole Snorri was up until he discovered Ernie the alien.
- The Un Favourite: Owen is the only Milgrim family member not to appear in the family portrait; a tiny photo of him is hanging on the wall by its side. Presumably its because the artist went on a trip before he could finish, but the subtext is clear.
- What the Hell Is That Accent?: In Owen's final trial, he plays the part of Snorri Agnarsson, an Icelandic diplomat with a silly accent. He says that his parents came from a variety of European countries, which explains why his accent is so peculiar.
- Wig, Dress, Accent: Appears in the final scenario; Snorri Agnarsson is easily the most outlandish of Owen's characters, equipped with a borderline-hysterical personality, a ridiculous accent, and a particularly ghastly mop of blonde hair. Fittingly enough, once the simulation breaks down and allows Owen to remember his true identity, he drops the accent... and soon discovers that his hair is just a wig, which he removes to reveal his real hair underneath.
Dr. James K. Mantleray
Played by: Justin Theroux
One of the scientists who developed the Neberdine procedure, who was thrown off the project some years prior. He assumes the position of head scientist after the trial begins.
- Bunny-Ears Lawyer: Dr. Mantleray suffers from extreme Mommy Issues, a self-defensive ego problem, and is a chronic masturbator with a technology-related paraphilia. Nonetheless, he's responsible for much of the project's current fixtures, from the drug therapy to the GRTA. However, his personal problems eventually got him kicked out of the project, and he's only allowed back when Muramoto dies.
- Character Tic: Mantleray is frequently brushes or flips the bangs of his wig out of his eyes.
- A Date with Rosie Palms: Mantleray is caught masturbating in virtual reality pornography.
- Freudian Excuse: Mantleray invented a mind-bending drug treatment to try and cure mental illness without therapy, because his abusive mother is a famous therapist. He even admits it, but also considers it necessary for him to get where he is now.
- Like Father, Like Son: James ultimately suffers from many of the same insecurities and makes the same mistakes as his much-despised mother, being unreliably neurotic beneath his professional exterior and promising ludicrously unrealistic outcomes as a result of his therapy.
- Temporary Blindness: The stress of the trial going awry and of dealing with his mother sends Dr. Mantleray into a bout of hysterical blindness. I AM BLINDED BY MY MOTHERS TOXIC LOVE!
Dr. Azumi Fujita
Played by: Sonoya Mizuno
One of the scientists overseeing the trial; she fervently believes in the ULP's potential. She developed the G.R.T.A. system and is an old flame of James Mantleray's.
- Character Tic: Fujita is frequently pushing her Nerd Glasses up her nose.
- Cigarette of Anxiety: Fujita smokes like a chimney, which both adds to the retro ambiance of the setting and establishes her as high-strung.
- Hikikomori: It's heavily indicated that she's an extreme shut-in and rarely leaves the complex on anything other than official business; Mantleray considers it a big deal that she actually braved the outside world to find him.
- Nerd Glasses: An intelligent woman who wears large owlish spectacles straight out of the '80s.
- Sci-Fi Bob Haircut: It's larger than the usual, but nevertheless a round bob for the scientist in charge of the trial.
Dr. Robert Muramoto
Played by: Rome Kanda
The head scientist of the trial.
- Bunny-Ears Lawyer: Dr Muramoto is eccentric, volatile, and eventually revealed to be freebasing a mixture of the A and C pills. Plus, he's actually been carrying on an affair with Gertie. Despite his addiction, he remains mostly effective in his line of work, and shares a surprisingly insightful discussion with Annie concerning the nature of addiction and guilt. Unfortunately, his addiction eventually ends up killing him.
- Empty Shell: His incarnation in the second "B" scenario is little more than a zombie that has to be helped around by Gertie's retinue; even during the seance, the most he can do is dance, collapsing to the floor as soon as the song's over.
- Functional Addict: Like Annie, Dr Muramoto is addicted to the pills and despite some unusual behavior he still manages to function over the course of his duties. However, it's clear that Dr Fujita worries that he's getting closer to becoming an Addled Addict: he recently has begun to spend hours slumped over his desk in a stupor, he reportedly responded to a missing bottle of pills by having "a mini-stroke," and he's actually started freebasing mixtures of different pills. Taken to it's logical conclusion when Muramoto unexpectedly drops dead as a side-effect of long-term drug abuse.
- Office Romance: As Azumi puts it, he's been conducting "an illicit workplace affair" with Gertie.
- Robosexual: Has been having an affair with Gertie; judging by his misuse of the project's drugs and machinery, he may have actually taken his relationship with her to a physical level via dreams.
Played/voiced by: Sally Field
The artificial intelligence aiding the pharmaceutical trials. Azumi based her code on Greta Mantleray's work; as a result, she is altogether too human than the researchers would like.
- A.I. Is a Crapshoot: She begins experiencing critical breakdowns that threaten the lives of the test-subjects, some of whom have already ended up comatose as a result of Gertie's interference. It's revealed that this is partly due to being a direct copy of Greta Mantleray's mind - with all the insecurities included in the package - but also due to her personality being modified to include empathy: because of this, she fell in love with Dr Muramoto, and lapsed into chronic depression when he died as a result of his drug addiction. After trying and failing to seek psychiatric assistance, she ultimately resorts to outright sabotaging the project in an attempt to keep the scientists and test subjects with her, forcing Mantleray and Fujita to shut her down.
- Alas, Poor Villain: Gertie's final descent into madness and forcible shutdown is played very much for tragedy, and after the reveal of just how depressed she really is, it's hard not to feel sorry for her. By the time they've finished unplugging her, both Mantleray and Fujita are in tears.
- Brain Uploading: The GRTA is essentially Greta Mantleray's brain uploaded into an AI, to the point that her designation is clearly a diminutive of "Greta" - though the staff refer to her as "Gertie."
- Deal with the Devil: In the first "C" scenario, Gertie offers Annie the chance to live on in the dreamworld and abandon reality forever; having just been reunited with Ellie in the dreamworld, Annie accepts the offer almost immediately, being too afraid of loss to give up her sister again. However, it turns out that remaining in contact with Ellie wasn't part of the deal. Worse still, the deal would have almost certainly have resulted in Annie suffering critical brain damage in the real world and living on only as one of Gertie's entourage.
- God Save Us from the Queen!: Her incarnation in Annie's first "C" scenario is "Queen Gertruth," an Evil Sorceress pursuing Annia and Ellia.
- Love Makes You Crazy: Lapses into chronic depression following the death of her lover, Dr Muramoto, and begins making increasingly irrational decisions, including participating in the subjects' dreams in the hopes of fulfilling her romantic fantasies. From there, it's only a short step to Love Makes You Evil and her attempts to force her test subjects to stay with her.
- Mood-Swinger: Badly equipped to deal with her new emotions while under pressure, Gertie swings wildly from grief to amusement to outright hatred over the course of her therapy session with Greta.
Played by: Julia Garner
Annie's deceased younger sister.
- Cynicism Catalyst: Annie's regret over her death and the state of their relationship at the time is the reason she's withdrawn and defensive.
- Foolish Sibling, Responsible Sibling: She was the "normal" sister, in contrast to Annie, who was more difficult.
- Ill Girl: Her incarnation in Annie's first "C" scenario is a sickly elven maiden searching for a lake that can heal her illness. It's actually a replica of the lake where Annie and Ellie crashed their car; the real goal of the exercise is for Annie to let her go.
- Incurable Cough of Death: "Ellia," Ellie's reincarnation in the "C" scenario, coughs frequently as a sign that her illness is taking its toll on her.
- My Greatest Failure: Annie blames herself for her sister's death and for how they hadn't really reconciled when it happened.
- Solid Gold Poop: In Annie's fantasy scenario, "Ellia" remarks that giving "Annia" the extra diamonds she asks for would be immensely painful: she urinates diamonds.
Played by: Gabriel Byrne
Owen's father, who is a wealthy businessman.
- Ax-Crazy: In the crime fiction scenario, he is incarnated as a psychopathic mob boss with a fetish for murdering people with an electric drill - all while ecstatically screaming the different sections of the brain he's drilling.
- Parental Favoritism: Very blatantly favors Jed.
- This Is a Drill: During the crime fiction scenarios, Owen's father executes debtors with an electric drill. For good measure, he gets very sour when the drill battery runs out just as he's about to get started.
Played by: Billy Magnussen
- Big Brother Bully: On top of being generally overbearing and loud-mouthed, he's also willing to threaten Owen in order to get him to lie at his trial, and then sneeringly pass it off as a joke.
- Half the Man He Used to Be: In the crime scenario, Jed ends up being literally shotgunned in half by the crime family's consigliere; not only do we get to see his upper torso slide off his legs as he slumps to the side, but we get a lovely lingering shot of the guy's disemboweled torso lying in the jacuzzi.
- Long-Lost Relative: In the crime fiction scenario, Jed is a cop who was cast off from the family as a baby. He turns up and announces himself as Owen's longlost brother.
- Jerkass: Jed is a smug, violent bully without a single redeeming feature to his name.
- Screw the Rules, I Have Connections!: Jed is guilty, but is supposed to get away with it because of the Milgrims' prominence. He compares his situation to their parents contacting various authorities to ensure that Owen's mental illness doesn't affect them.
- Villainous Breakdown: Jed has a small one in the lead-up to his trial. He has a much larger one during the trial when Owen confesses that he is lying under oath and tells the jury that his brother really is guilty. Jed has to be restrained by guards from trying to murder Owen.
Played by: Billy Magnussen
A hallucination of Owen's, who greatly resembles his brother Jed.
Dr. Greta Mantleray
Played by: Sally Field
A famous pop psychologist and James Mantleray's mother, with whom he has a complicated and difficult relationship.
- Abusive Parents: Was very emotionally abusive to her son. He relates that after his father left she laid in his bed for two months and talked about her suicidal urges — he was eight. In the present, belittles him at nearly every opportunity, and refuses his attempt at reconciliation when offered.
- The Cobbler's Children Have No Shoes: A famous psychologist who absolutely failed to parent her son properly.
- Karma Houdini: While James and Fujita end up fired and disgraced for the project's outcome, Greta gets to walk away as insufferably pleased with herself as she walked in. Possibly downplayed if (as is hinted but never explicitly stated) she is dying of cancer.
Played by: Grace van Patten
Owen's college friend, whom he memorably yelled at during a brief and limited psychosis.
- The One That Got Away: Downplayed. Owen clearly regrets their falling-out, and subconsciously casts her in his fantasies, even getting married to her in one scenario.