Monroe Sisters

Monroe Sisters is the friendship between Grace Monroe and Hazel from the Infinity Train fandom.

Canon
Grace Monroe is a young woman who got abducted by the titular train as a child, but due to a lack proper guidance, she ended interpreting the train's number system as a measure of power and started a cult which she named "The Apex" worshipping the "Conductor" by encouraging any child she finds on the train to wreak as much havoc to the sentient denizens minding their own business on the cars to get their numbers as high as possible.

However, in "The Musical Car", she and her co-leader Simon Laurent are separated from the cult due to the new Conductor who actually tries to offer some guidance to passengers, routinely detaching faulty train cars created by the previous conductor to put into quarantine.

In "The Jungle Car", they end up running into a little girl named Hazel who befriended a denizen, a motherly purple gorilla named "Tuba". Immediately, Grace and Simon forge plans to indoctrinate Hazel to their cult by separating her from Tuba, when both of them are out of earshot. When they explain their own number system to Hazel, she is excited to show them her number, but Grace is genuinely concerned for the girl when her number doesn't glow. Since Simon's plan to get Hazel to abandon Tuba fails since Hazel is as attached to her as she would be to her own mother, Grace reluctantly allows the gorilla to accompany them.

In "The Debutante Ball Car", Grace actually starts to bond with Hazel when the group is forced to dance in the titular car, since they have to keep a low profile in front of Hazel. She tells Hazel that she has bad experiences with dancing, since her parents forced her to do ballet as a child, but then didn't bother to pick her up and she couldn't have ice cream with her other dancers since none of them liked her. Hazel in turn is aware that she should have parents, but she is frustrated when she reveals to Grace that she doesn't remember ever having them. When the group puts on an excellent performance, Grace is initially happy but then realizes that her number dropped because of Hazel's influence, to her shock.

In "Le Chat Chatet Car", the group is braving said car while it's snowing inside. To offset his frustration, Simon throws a snowball at Grace, causing a snowball fight between all of them. Even the sentient water has fun making a blizzard, with Grace noting how strange it is that Hazel isn't getting hypothermia despite wearing nothing but a short-sleeved shirt and shorts. They reluctantly end up taking shelter in the Cat's winter vacation home, despite Grace and especially Simon having bad blood with the Cat. During their stay, Grace admits to Simon that she's worried that her number is going down, thinking that Hazel is somehow weakening her.

In "The Color Clock Car", to work on Roy the Color Clock's puzzle, the group has to separate into two, Simon IS upset that he is not sorted into the same team as Grace, having to go with Tuba instead. The intent of the train was to get both groups get along better, which seemed to be working initially. But the conductor's scan causing that car to be put into quarantine while all four of them are inside of it leads to Tuba hanging onto the car for dear life and Simon offering to "save" her while Grace and Hazel save themselves by proceeding to the next car. However, neither of them expected for Simon to ignore his conscience and use this opportunity to truly show his hatred of the denizens, stomping on Tuba's hands and letting her fall right into the train's wheels. When he returns to Grace and Hazel, he gleefully tells the latter that Tuba is gone, not only breaking Hazel's spirit but also causing Grace to lose trust in him. When Grace tries to go outside to try and console a heartbroken Hazel, she witnesses the poor girl uncontrollably shifting into some kind of turtle humanoid.

In "The Campfire Car", Hazel finds out that she isn't a human, but was a denizen the whole time. When Hazel asks Grace if she hates her now, Grace realizes that all of the denizens she intentionally hurt for years were sentient beings with emotions just as complex and valid as her own. She instead comforts Hazel, agreeing that Simon will most likely hate her if he ever finds out and offers to keep it their secret. Hazel hugs Grace in return, managing to shift back into a human to appeal to Simon. However, they ignore Simon's demand to keep going to reach the rest of the Apex, Hazel insists on holding a funeral for Tuba. Grace accompanies her as Hazel climbs very high onto a tree, holding a glowing crystal Tuba gave her earlier and singing the lullaby Tuba always sang for her when she was sad. Grace is so moved by Hazel's eulogy to her adopted mother that she visibly starts to cry, but she attempts to hide it. She then hugs Hazel, proud of how emotionally mature she is. When they return to an impatient Simon, Hazel does her best to keep her emotions in check, not wanting to transform in front of him. When Simon gives Grace flak for encouraging Hazel's desires to "waste time", Grace defends her and tries to appeal to Simon's own trauma with the Cat, to no avail. Reluctantly, the two of them accompany Simon as they leave for the next car, only to pass a strange woman on their way. The woman ends up following them, accusing them of meddling with the train cars.

In "The Canyon of the Golden Winged Snakes Car", the group finds out that the woman is Amelia Hughes. Simon is in complete denial about Amelia's words, to the point where he leaves the group to rant to the Cat about Grace not being like she "should be" and Amelia telling "lies" to him. However, Grace stays with Amelia and Hazel and is actually willing to hear the former out, finding out that the cars being moved has nothing to do with them, a corrupted piece of code has been found in them, seemingly moving independently on the train.

In "The Hey Ho Whoa Car", Amelia reveals the truth about the Conductor the cult worships, she herself ursurped the title from the true conductor, One-One, meaning that the entire philosophy of the cult was a lie the whole time. They also find out that Hazel herself is the corrupted code, being a botched attempt of Amelia to bring her husband back to life with the train. Pressured by Simon and conflicted between her friendship with him and her newfound protective instinct for Hazel, Grace decides to take a middle ground by calling Hazel a "null", a slur for denizens made up the Apex. This convinces Simon that Grace didn't know that Hazel was a denizen, but he nonetheless uses microbes to dig into her memories. Seeing the scene of Grace promising Hazel not to tell Simon, the latter angrily breaks into tears.

In "The Origami Car", Grace still offers Hazel a place to stay with the Apex. Hazel however admits that she no longer feels safe around her, preferring to go with Amelia so she can be studied on. When Hazel leaves with Amelia, Grace breaks into tears as Hazel gives her an emotionless "Goodbye, Grace", with Simon watching with complete disdain. However, when Simon expects Grace to get over it immediately so things can go back to "normal", he is frustrated that Grace is still attached to Hazel. Grace angrily tells him that Hazel was her friend, Simon uses the memory device to flash her, snapping at her that he was her "friend" first. Simon leaves her trapped in her memories as he steps on the origami citizens on his way back to the Apex.

In "The New Apex", within her memories, Grace is tormented by her conscience assuming the form of Hazel, having her own friend call her out for her cowardice. Managing to make it out after an unstated amount of time, Grace tries to patch things up with the Apex, motivated by not being able to do the same thing for Hazel. However, Simon had gone completely mad when he was gone, having turned the Apex against Grace. It results in a fight between the two former friends, with Grace managing to save Simon and gaining the trust of the Apex back. However, Simon crosses the line to outright trying to murder Grace when she thought she was safe. Grace manages to survive due to being saved by the origami denizens she helped earlier, but Simon meets his demise when his mad laughing attracts a Ghom who sucks all the life out of him. Despite her losses, Grace still comes clean to the Apex and allows all of their numbers to go down as she reveals the truth about the train to them.

Fanon
Given that it is the focal point of the most well-received book in the series, the platonic relationship between Grace and Hazel is very popular in fanwork.

Fandom

 * FAN FICTION