Grace Monroe

Grace is an 18-year-old woman initially shown to be sociopathic and amoral in her actions, justifying them by saying that she is a passenger and was entitled to get whatever she wants, and seemed to be incapable of feeling remorse or guilt. She was charming and manipulative, recruiting hundreds of children on her side and brainwashed them into thinking bringing their numbers down and improving themselves was a weakness. She held a delusional belief in worshipping the Conductor Amelia to the point of establishing a cult-like gang dedicated to her, and had no qualms in killing or using people and denizens just to get what she wanted, once allowing Apex member Lucy to shoot herself in the eye with a harpoon gun.[4]

Due to arriving on the Train while it was under the control of Amelia, Grace originally believed that One-One is a usurper and maintained a twisted belief that the goal was not to bring your number down so you can exit the train, but to have the highest number possible. She also believed that the residents of the train are "nulls" ("not even a zero"), and did not even believe they could think for themselves, demonstrating her former Social Darwinist beliefs, inspired by Lord of the Flies and an unnamed book from which she got the title of "The Apex".[5]

Grace's character design is that of a young African-American woman with short dark hair in dreadlocks. Like all members of the Apex, she has a red horizontal squiggle line across her face, based on the oscillating eye of Amelia's robotic suit as "The Conductor". Her outfit is a pale orange top with two shoplifting tags on each sleeve and a red and purple triangle pattern on the trim of the sleeves over a pink bra with grayish purple shorts, gold earrings that resemble upside-down exclamation marks, a green fanny pack, purple kneepads and pale red sneakers. Her disguise, used to bypass denizens including Samantha the Cat, consists of a black robe, a yellow mask (lost in "The Musical Car"), and grayish-purple opera gloves, one of which hides her number. In "The Debutante Ball Car", Grace wears a ball gown with the same color scheme as her usual outfit and puffy sleeves. Her hair is tied back using a headpiece with three orange feathers, she wears a yellow choker with a white diamond, and keeps her earrings and opera gloves. As of "The New Apex" she gets rid of her Apex Mark as a sign of beginning to redeem herself.[6] She was designed by Megan Phonesavanh, who modeled some of the Apex children on childhood photos of members of the Infinity Train crew.[4]

Before boarding the Infinity Train, Grace grew up in a wealthy family, under neglectful parents who hired various assistants to watch her rather than spend time with her personally. After being arrested for shoplifting in an attempt to acquire attention and still ignored by her parents, Grace boarded the Infinity Train after it appeared before her. Seven years prior to the beginning of Book Three, she briefly encountered Amelia in her robotic suit inside the Pumpkin Car, her appearance at the time as "The Conductor" leaving a lasting impression on her. Sometime after this, she became friends with Simon after saving him from a Ghom, a parasitic creature from outside the train. When Simon questioned why she had a higher number on her hand than his, her competitive nature caused her to claim that the goal of the train was to increase her number. Together they formed the Apex, a cult worshipping their image of Amelia and deriding One-One, who they believe to be a "False Conductor" instead of Amelia, as well as teaching that the native denizens of the train (which they dub "nulls") are their playthings, non-real beings to be done with as they desire, with those they perceive as being more dangerous to their way of life to be "wheeled" (pushed off the train in-between carriages and crushed beneath the wheels of the train, killing them). Grace is inferred to have previously killed many such denizens in this fashion.[7][8]

In Book One, Grace is briefly glimpsed onscreen in the passenger records hijacked by Amelia.

In Book Two, a masked Grace is introduced towards the conclusion of "The Lucky Cat Car", where she and "The Apex" loot a train car being overseen by The Cat. She then takes Jesse and MT to the Mall Car, where she introduces the pair to The Apex, and also Simon Laurent, her second-in-command. She then takes Jesse to the Cube Car where Jesse is forced to kick a sentient cube, making his number go up, while Simon and the Apex attempt to kill MT.[9][10] After Jesse saves MT, Grace reveals herself and Simon to love terrorizing the "Nulls" of the train and that they are nothing to her, and should not be seen as people. After his number reaches "0" and he is unwillingly removed from the train, leaving MT behind, Grace expresses disappointment at Jesse's choice, with Simon calling Jesse weak, and Grace correcting him to claim Jesse was only misled. The pair then attempt to kill MT before she flees the car.[11][10]

In Book Three, after being separate from the Apex alongside Simon, Grace's experiences with 6-year-old Hazel and her gorilla companion Tuba begins to cause her to be more open-minded as she gradually becomes more kind-hearted and sympathetic toward denizens, even referring to them by their actual names and titles, instead of just calling them all "nulls" and even saying that Tuba is one of the good ones instead of seeing them as all evil.[12][13] When Simon murders Tuba in cold blood per Grace's original plan, Grace is visibly shocked and angered, although it is unclear if this was because of her gradual friendship with Tuba or because Simon blatantly disobeyed her order to not kill Tuba.[14][15]

After finding out from Amelia that One-One is indeed the true conductor and what he said about getting the number down was true she was ashamed for her past misdeeds. She begins to show true compassion toward denizens, and even removes her Apex mark. After Hazel left with Amelia for her treatment of her and Simon tried to get rid of her for her abandonment of her own philosophy, Grace decided to fix her mistakes, starting by helping the kids in the Apex getting their numbers down and stop telling them how they should be. It is also shown that Grace does show poignant sadness when she lost people she deeply cares for, such as crying agitatedly when Hazel left her, and after witnessing Simon being killed by a Ghom and him being reduced to ashes.[16]

Grace and Simon used to be the closest friends after Grace rescued Simon, who was unwittingly abandoned to a Ghom by Samantha the Cat, and they formed the Apex together, a group who aim to vandalize the train and attack its denizens to keep their numbers high. A deleted scene depicts the pair as having been briefly romantically involved in their youth.[17] Although they once shared their ideology together, their relationship soon decayed after Grace met Hazel and has softened up to denizens, which was only aggravated after the death of Tuba and Grace being forced to save face in front of Simon, who grew to distrust her. Eventually, Grace was being considered as a void by the deranged Simon who swore her as his enemy and nearly got murdered by him, even after she tried rescuing him. Despite their broken friendship, Grace realizes her mistakes of how she made him believe in lies and was heartbroken when a Ghom killed Simon. After realizing that their entire philosophy was wrong and became truly sorry for how horribly she treated denizens, Grace dissolves the Apex in order to turn it into a new group dedicated to getting her followers' numbers down to zero so they can leave the train.[18]

• Official website of Infinity Train – Cartoon Network
• Official website of Infinity Train – HBO Max