After losing everything she's worked for and with the war for Etheria seemingly over, a barely conscious Catra is wallowing in guilt and self-loathing when a odd vehicle appears in front of her. With nothing left to lose, Catra boards it and soon discovers that she's the newest passenger on the Infinity Train, an extra-dimensional Epiphanic Prison that will only let her leave once she's solved all her problems. Thankfully, she isn't alone, as she soon meets another new passenger by the name of Steven Universe, who has boarded the train thanks to his life also being in the midst of falling apart. Deciding to become companions, the duo work together to explore the train, making friends and enemies as they struggle to return home.
Meanwhile, the worlds they have left are spinning along despite their disappearance. How exactly will Adora and the Rebellion fare in the fight against the intergalactic Horde Armada if Catra isn't present to pull a HeelFace Turn and begin aiding them? And how will Beach City and Gem Homeworld cope when they realize Steven can't be found anywhere in the galaxy?
The story is ongoing.
Peace of Mind, Piece of Heart contains examples of:
- All-Loving Hero: Steven retains this quality from his home series, being incredibly amicable to every denizen he and Catra encounters.
- All of the Other Reindeer: Butter Brickle, a popsicle child, is shunned by his community not only because he managed to survive a violent passenger raid that claimed the lives of many others a few years ago, but also because he continues to befriend all the travelers that pass through the train car.
- Alternate Dimension: Steven theorizes that the train both exists in one, as well as picks up travelers from various others, when Catra shows no familiarity with the Gem Empire.
- Armor-Piercing Question: In order to stop Steven from continuing an impromptu musical number in Chapter 3, Catra asks why Steven even wants to leave, since he seems to be enjoying himself so much. This shuts Steven up and leaves him completely shaken, even causing his number to rise back up slightly.Catra: (singing) "Maybe everyone is no one that you know; If you love this place so much, why do you even want to go?"
- Beyond Redemption: Invoked. Catra rebuffs Steven's attempts to learn more about her on the basis that she's guilty of far too many atrocities to deserve any sort of kindness.Catra: "Dammit! Dont you know a lost cause when you see one?"
- Both Sides Have a Point: Micah and Shadow Weaver both make valid points in their argument over whether sending Adora, Bow, and Entrapta to rescue Glimmer was a good idea. The former makes the case that her rescue would be a boon for the Rebellion forces and that everyone involved desired to undertake the mission. The latter argues that, while that's certainly true, it doesn't change the fact he just sent their most skilled warrior, tactician, and engineer on what could easily be a Suicide Mission to find someone who may not even be alive.Shadow Weaver: "Well, yes, Glimmer's return would provide us an essential component needed to properly utilize the heart, but without She-Ra we would still be lacking a key requirement. More importantly, you have no guarantee that Adora will actually be able to liberate Glimmer. You've put so much at risk for one person.
Micah: "First of all, this was not my personal choice. I am king of Bright Moon but I do not make unilateral decisions for the Rebellion. Secondly, for all the confidence you seem to have in Adora as an asset in this war, you don't seem confident she can complete this mission. Do you not think she can save Glimmer?"
Shadow Weaver: "None of us have any real comprehension of the strength or resources of Horde Prime, though we do know that he has a vast fleet and a sizable army operating under a hive mind. While Adora could prove a key role in carefully planned battles and operations on Etheria, you've allowed her to race off into a situation where Horde Prime holds every advantage. And moreso, you don't even know for sure that Glimmer is even alive."
- Cat Folk: Catra, with Steven excitedly calling her a cat girl when first meeting her, much to her embarrassment.
- Call-Back: To numerous events in She-Ra and the Princesses of Power and Steven Universe, naturally.
- When explaining reasons why Steven shouldn't want to get close to her, she specifically mentions opening "portals that nearly destroy reality" and ruining "stupid, stuffy proms".
- During the third chapter, Steven sings Haven't You Noticed (I'm a Star) on a dare, and later improvises a number that peppers in lyrics from Sadie Killer and the Suspects and On The Run when trying to cheer Catra up.
- Damsel in Distress: Glimmer is trapped in a Gilded Cage, but unlike in canon, Catra is no longer present as a sympathetic ear or comrade.
- Dramatic Irony:
- Micah and Shadow Weaver argue over the fact that they have no idea if Glimmer is still alive, though the reader is already aware that she is. Shadow Weaver does correctly point out the only reason why Horde Prime would let her live, however.
- When talking with Bow about her worries, Adora eventually reaches the topic of Catra and how she has basically disappeared, with an errant comment from Bow making her realize that the lack of Catra might be because she's dead. Of course, the reader knows that Catra is just traveling the train.
- Epigraph: Every chapter begins with one of these.
- Foil: Catra and Steven serve as this to each other. The former is an AntiVillain, grew up as The Un-Favourite, is a jerkass who secretly cares deeply about others, and revels in using violence when she has the chance. The latter is an undisputed hero who grew up being loved and supported by pretty much everyone he meets, and is in turn an extremely kind and empathetic person (who secretly holds some negative thoughts he'd desperately like to ignore), and will always go the pacifist route unless there is no other option.
- For Want of a Nail:
- The fanfic takes place during the final season of She-Ra, with Catra boarding the train taking the place of her and Glimmer's confrontation, and thus their combined abduction, at the end of season four. The B-plot of the fanfic explores what has changed as a result of her absence, such as Adora having to use a variation of the plan from "Save the Cat" in order to save Glimmer, as Catra is no longer available to teleport her over.
- The fanfic also takes place towards the end of Future, after the events of the episode "Mr. Universe", with Steven boarding the train taking the place of him running away to train under Jasper in the following episode.
- Heroic B So D: Steven suffering from this after having an apparent falling out with both his girlfriend Connie and his father Greg in the days prior is what summons the Infinity Train to him.
- History Repeats: After Steven has a Pink Steven episode, Catra notes that she and him have apparently fallen into a similar routine to the one she had with Adora.Catra: If were not saving each other, were trying to kill each other. Who does that remind you of?
- Idiosyncratic Episode Naming: Mirroring Infinity Train, each chapter follows a "The [Noun] Car" format.
- Ignored Epiphany: Catra pushes a little cat girl named Marmalade down a slide to help her get over her fear of the slide; Marmalade gets hurt and becomes afraid of Catra instead. Even though Marmalade was hurt and crying, and her friends Mochi and Rascal call out Catra for what she did, Catra just runs away, denying to herself that she did anything wrong.
- Innocently Insensitive: Catra is excited and impressed with her first glimpse of Pink Steven, not realizing its true nature or his feelings about it immediately, though she catches on pretty quick.
- Jerk with a Heart of Gold: Despite her jerkass behavior, Catra does attempt to cheer others up when they're feeling down, and will occasionally acknowledge when she's hurt Steven's feelings and reluctantly apologize to him.
- Late-Arrival Spoiler: Don't read this fic if you didn't finish watching She-Ra (2018) and Steven Universe Future. The Reveal at the end of Infinity Train Book 1 is also immediately spoiled.
- Living Lie Detector: The pillow girls in the Slumber Party Car are this, knowing when someone is lying when they play Truth or Dare. Naturally, Catra lies when she's asked a personal question, causing the girls to become distressed and make the cloth world of the car start coming apart. Steven is knocked unconscious by a falling foam star when they try to escape, so he doesn't know how Catra managed to get them out, but he assumes she had to begrudgingly tell the truth.
- Love Epiphany: Bow tells a sleeping Adora that he has retained memories from the third season's Lotus-Eater Machine, and one of them includes a moment when he and Glimmer shared a kiss, making him realize that he has romantic feelings for her and wonder if Glimmer also remembers and feels the same.
- Musicalis Interruptus: Catra intentionally tries to pull this off at the end of Chapter 3, succeeding when one of her remarks stops Steven's song and the car's accompanying music dead in its tracks.Catra even thought she heard something approximating a record scratch, though she had no idea what could have caused that.
- Musical Number Annoyance: Catra's reaction to Steven suddenly bursting into song in Chapter 3, though it was more slack-jawed confusion until he started making cat puns.
- Obviously Evil: When Catra states that, while she figured it out pretty quickly, no one in the Horde really thought of themselves as "villains or anything", Steven points out that they literally lived in a place called the Fright Zone. He even brings it up against later, incredulously noting that her caretaker was named Shadow Weaver.
- Ontological Mystery: Averted. Since this takes place after Book 1 of Infinity Train, Catra and Steven are fully aware of the train's purpose and the meaning of the numbers thanks to One-One's introductory videos. However, they're still at a complete loss as to how to accomplish the "fix their problems" part of the equation, and Steven is flustered about how the train functions in general.
- Pet the Dog: One of Catra's first actions on the train. Though she's at first indifferent to Butter Brickle, who was showing her the way to leave the car, she become sympathetic to him when he reveals that he's an outcast with no friends. Catra encourages him to stand up for himself, even agreeing to be his friend regardless of whether they actually see each other again. Her number comes down for that act of kindness.
- Reformed, but Rejected: Discussed. When talking about the broken pedestal he now holds for his mother, Steven muses that redemption is different than forgiveness. When asked by Catra to elaborate, he explains that while one can definitely work to become a better person, no one is actually obligated to forgive you for everything you've done prior to that; by the same token, people can forgive you even if you think you don't deserve it.Steven: "Redemption is you and forgiveness is them, basically."
- Riddle for the Ages: Steven unloads several of these about the train, mainly concerning how the train cars move and the general capabilities of the train such as its possible ability to access other planets and dimensions. Catra throws in her own guesses after Steven prods her for input, but couldn't care less for the most part.
- The Short War: According to Steven, when he first entered The Chocolate Car, four kinds of chocolate were in a long-standing civil war. Steven managed to end the conflict in a week. Catra, who herself just came from the middle of a decades-spanning conflict, is incredulous.Catra: "So, yeah. How did you end a war in a week? Positive energy and the power of friendship?"''
Steven: "Kinda, in part. Also some reconstruction, halting a few battles, saving some bystanders. It was a process."
- Screw This, I'm Outta Here!: Catra pushes a little cat girl named Marmalade down a slide to help her get over her fear of the slide; Marmalade gets hurt and becomes afraid of Catra instead. When Marmalade's friends Mochi and Rascal call out Catra for what she did, and a crying Marmalade asks why she did it, Catra runs away in anger.
- Tantrum Throwing: Bow does this when he fails to prevent Glimmer's abduction, angrily shooting his arrows at the sky before breaking down in tears.
- Tough Love: Deconstruction. Catra attempts this with a cat girl named Marmalade she meets in her second car, forcibly pushing the scared child down a large slide. The kid gets hurt in the process, with Marmalade's friends and the child herself, calling out Catra for her unnecessary violence, causing Catra to run away out of guilt.
- Tranquil Fury: Downplayed. Horde Prime's reaction when Glimmer attempts to escape in Chapter 2 is more annoyance than anything, but it's still enough to make him switch tactics from what would have been a non-violent interrogation session to torture.
- Two Lines, No Waiting: So far, Steven and Catra's adventures on the train have been juxtaposed with the events of She-Ra season five.
- Villainous BSoD: Catra suffering from this after receiving a "The Reason You Suck" Speech the end of "Destiny: Part 2" is what summons the Infinity Train to her.
- What the Hell, Hero?: A little cat girl named Marmalade's friends Mochi and Rascal call out Catra for pushing Marmalade down the slide and getting her hurt. Catra justifies herself by saying that she just pushed her down a slide. Mochi fires back that that's not the point, and that she hurt Marmalade and made her more scared than she already was. When Catra continues to deny she did anything wrong, Marmalade tearfully asks Catra why she did it, causing Catra to run away in anger.
- You Remind Me of X: Steven's bright colour scheme and use of magic has Catra mentally associate him with Glimmer, right down to giving him the nickname "Sparkles". Steven saving her after nearly hurting her during a Diamond outburst also has her think of her complicated relationship with Adora.
- You Wouldn't Like Me When I'm Angry!: Like in Future, Steven's diamond abilities manifest when he's overwhelmed with emotion. Nearly getting injured on an assembly line in The Gear Car triggers traumatic memories of getting stomped on by Yellow Diamond which causes his powers to go berserk and destroy the entire factory.