Chapter Text

The writing

I wrote this in what can be described as a two-day long semi-fugue state. I am so sorry if you tried to talk to me during those two days because I was NOT there. The first day was plotting + writing out all of the dark, angsty scenes. Every time I felt I could not go any further because it was too heavy, I found another foothill down. It very much felt like trying to take apart Ed one piece at a time to try and understand what he was made of. The second day was finding the light at the end of the tunnel. Bringing back in the joy and hope. I found an ending that was emotionally satisfying and happy. All subsequent editing has felt like adding lanterns between that bleak beginning and the light at the end.

Normally writing is a very deliberate activity. What is the plot engine? Who is moving things? What do they want? What are the limitations? But this fic felt like a story that just came to my brain fully formed. I sat down, spent 6 hours organising the scenes and the order in which I wanted them, and then wrote them.

I think part of the reason this fic just came out mostly clean is that I have been into FMA for over a decade. I never wrote fic for it because it has felt like a ‘complete’ work. What angle do I have? With other fandoms (eg Naruto) I see wide gaps that are unsatisfying and curious. With FMA I’m like, wow, that was good! (This is the same reason I wouldn’t write for Andor even though I adore it).

So I decided to put together a lot of smaller AUs. I think I included all the AU/headcanons I have had except for one (transmasc Ed).

A list of the AUs/headcanons I reference:

• Ed in Ishval
• Second/third gen Xingese Mustang and Izumi
• Ed learns bits and pieces of Alkahestry
• Ed writes letters to his dad
• Ed trades up something else at the gate
• Al gets his body back earlier but stays in Resembool
• Greedling survives the Promised Day
• Ed can ‘feel’ various different compounds
• Ed and Al’s souls are entangled — Ed gains a sort of ‘regen’ ability as a result

I want to do more with less. Ed is very much passively suicidal and is searching for forgiveness. He is also not going to admit that out loud. I also did not want to make this a ‘let’s solve mental health issues’ fic. This is also why Ishval is not graphically described. Scar doesn’t appear either. This fic has a very narrow scope and premise. I did not want to add 8k about war, genocide and reparations when I could not do it justice.

The Ed in this fic would have no qualms on using a Philosopher’s Stone to fix his body. He’s already made so many mistakes. What’s one more? The difference is that Ed sees his body as atonement for the mistakes he has made. A constant reminder.

Sometimes you find a piece of media that takes your perception of what is possible and stretches it wide open. When I first read FMA over a decade ago, it shook my idea of what a story could be. Especially of what an ending could be. Its fingerprints are all over my writing. The themes of, “what do we owe individuals?” (Love) vs “what do we owe systems?” (Power). Who do you love? What does the system owe you? Who will you bleed for? What parts of your humanity will you hold onto? You are playing a game, you know. Can you see the rules? Can you step outside it?

I adore a funky magic system. I love writing characters who are information-brokers. Spymasters, politicians, messengers, journalists, linguists, anthropologists, and of course, physicists. The biggest darlings I had to kill in this fic were physics/alchemy related. My god did I want to keep yapping about this and my lovely betas (who put up with my shit) kept on pointing out where it added bloat and abstraction.

However, now I will yap about it.

The science

Research Notes

As stated, if you’re a physicist, please fight me. I won’t win but we’ll both have a fun time.

The biggest assumption is the linking of the conservation of mass to equivalent exchange to information theory. The idea is: mass is an organisation of different atoms, particles, and the amount of energy that they contain. Is that not just information? So, what if information cannot be destroyed or created?

Entropy is — on a high level — the idea of decay. Disorder. It’s the reason why a star dies out. Or, why your work desk becomes cluttered if you don’t clean it up for three days in a row.

So okay. Information cannot be created or destroyed, it just becomes disorganised. Hence why CDs are not eternal. Or USBs.

What kind of information is then the most resistant to being scrambled by entropy? Good question. Go read Death’s End for an interesting answer. In the meantime, the answer I chose to with is ‘memory’. Ed’s memories of his mother especially. Since Trisha is dead, you cannot create more information (memory) about her. Therefore, the pre-existing information/memory becomes even more valuable.

I think white holes deserve more justice tbh. What a fucked-up sci-fi like idea? Information can leave but it can’t enter. The Truth cannot be altered by any external force. However, you CAN take a piece of it out with you.

I was trying so hard not to add fucked up algebra/group theory and standard model nonsense to Father’s nation-wide transmutation circle. Hello algebraic topology. I really wanted to link it with decoding theory. For context: a lot of the math that has to do with rotating or moving shapes (eg game dev/Unreal Engine) is also used in code-breaking and encoding information (e.g. ciphers, MFA, your email password). In other words: would it not be neat to create worldbuilding where I link together alchemical circles to the encoding and decoding of information?

So let’s talk about 0 = 1 -1.

This is vaguely based off of Hawking Radiation.

The idea is this: Father is trying to create a massive transmutation circle to bring down god. Lots of souls — information — being released outwards to do this. So, Hohenheim goes, “I’ll create an alkahestric diagram to suck in all the excess energy. Oh what would suck in energy? Collapsing down information. Oh what does that? A black hole. Let’s not compress information so hard it creates a black hole.”

They’re not setting out to create a black hole. But it’s a risk.

Ed goes, “Well that’s an insane idea. Sure I’ll help. But wait—in alchemy, there’s a moment where you go from deconstruction to reconstruction. What if I slip in during that moment on the Promised Day to change the toll? That way I can save Amestris and prevent anyone from having to pay the toll I did.”

Why a square? Well it’s got points. There’s also a joke regarding complex analysis and everything becoming a circle. But I could not find a place to put it in.

Ling’s along for the ride since Ed needs something to keep the ‘square’ transmutation open since energy can get clogged. What better as a power source than a Philosopher’s Stone?

Ed and Al are ‘entangled’. My entanglement I mean quantum entanglement. So you’ve probably heard that nothing travels faster than the speed of light. If this was not true, we’d have instant internet access all over. But quantum entanglement is the idea that two particles can share information instantaneously, even if they are somehow light years apart. I am doing some hand-wavey nonsense. But this is the idea why Ed and Al can experience being each other for moments. Al gets a lot more of it than Ed does.

Zero vs the null set is both a real and non-rigorous metaphor. I wanted to make a clever joke about measure = 0, but it doesn’t fit. But the fact that you cannot add anything to the null set is true.

Using the example of entropy and information-scrambling, Ed was able to pull Al’s body back out quickly enough that most of it was intact. Mostly.

The craft of writing sci-fi

You’ve probably heard of the term ‘hard/soft’ sci-fi. In other words, how academically rigorous is sci-fi trying to be? How accurate is it? Something like Star Wars is soft sci-fi. The science exists but it’s not really meant to be rigorous or get you to engage with it. Something like Project Hail Mary is hard sci-fi. It’s trying to be as accurate as possible and use pre-existing scientific ideas in a fun way.

Another axis is ‘cold/warm’ sci-fi. (Stealing this one from a friend). Cold sci-fi being more focused on the systemic and big-picture ideas of the science, with human impact being second. Warm sci-fi focusing more on the human and interpersonal aspect, which can come at the cost of the science. So, PHM is warm sci-fi because the people and hopefulness is more of the focus. The Three Body Problem is far more along the lines of cold sci-fi. It’s about the real, brutal, and earnest consequences of our actions and scientific discoveries and behaviour.

I have a stronger preference for ‘cold’ sci-fi. So the challenge with this fic was to not let the emotional heart of the story get lost despite all the science happening in the background.

Misc

The B-sides to this fic is (Greed)Ling going with Ed to create the square. Talking about Pascal’s wager. Ling sees Ed’s mental health shit from the outside-in. Amestrian vs Xingese differences in viewing queerness. Also, cultural differences. And all the linguistics worldbuilding I’ve been holding myself off from inserting into this fic.

Seriously. Drachma and Xing border each other. Does Helleno-Sinitic exist? Can you imagine Greek with Chinese tones? Unreal.

Also since FMA is set in fantasy Nazi Germany. If Ed is from the south and the mountains… does he speak the Amestrian equivalent of Bavarian? Even better, Swiss-German. Can you imagine him rolling up to the State Alchemist exam with that accent? For a comparison, this would be the equivalent of a child who speaks Scots or Cockney coming in to Cambridge and smashing the competition. Unreal.

If this sounds interesting for you, the books I’d recommend are:

• Gödel, Escher, Bach
• What We Cannot Know
• Determined (this is less of a direct reference — Sapolsky’s just got interesting ideas on metaphysics)
• Underlands (on grief and love and the world)
• Proto, if you want a nice primer on various (Indo-European) languages and how they changed
• I am loathe to recommend Stephen Hawking’s books now. But if you want a nice and accessible intro to various physics ideas, especially black holes, you should read them
• If you want an even better—but slightly more-in-depth—book on black holes, go read The Irresistable Attraction of Gravity. It’s written by one of the key scientists who worked on the pictures of the black hole that came out a few years ago.
• EDIT 18/06/2026: ThreeBlueOneBrown has an excellent new primer to information theory as a science.

Other influences:

• Reading the last third of Death’s End while listening to Square One. Iykyk
• Richard Feynmann’s letters to his dead wife. Hohenheim’s last letter references it. Seriously go read them. It’ll fuck you up
• ‘God does not play dice’ quote is from Einstein iirc
• ‘Death-awareness is the price we pay for cognition (self-awareness)’ is a modified quote from What We Cannot Know
• The scene where Ed ‘calls’ his mom is heavily inspired by a song in a foreign language about an injured man who roams the desert trying to sing to/call his dead grandmother

• Ed is this world’s equivalent of Paul Erdos. For context, Erdos was a very prolific scientist. He published so much research that there exists something called an ‘Erdos number’. I.e., how many degrees of separation is your research from Erdos’?
  • Go read ‘The Man Who Loved Numbers’ if you’re curious!
• I think the economics of Amestris are deeply fucked up and fascinating.
• I think you can create an analogy of Homunculi as 'removable singularities.' I'm not going into the details of this since I'm drafting a Pride!Ed fic that covers this. If you're curious for details, feel free to ask, though.
• Since 2023, I have had "In another life, I would have loved to discuss the metaphysics of being" pic in my face every week. I am so glad I can put that image to rest now.

Crit Notes

I aimed to write a piece of sci-fi that was engaging for both (1) the average person who has not touched science since middle school and (2) your career physicist/mathematician. I think I did not succeed at this. The science is too convolution for non-scientific audiences. The science is too handwavey for audiences with a scientific background. Could I have fixed this? Probably. But I wasn't in the mood to do another 3 editing rounds with sensitivity reading.

A big thing I am learning now is to think of 'story engines.' Which is a fancy way of saying, "Okay, what's the main thing moving the story along?" In this case, it was Ed's desire for atonement. There are two stories. The first is the slow revealing to the reader of what Ed has lost and suffered through. The second is what Ed is going to do. I like to think I got this one down decently.

The setups and payoffs are very satisfying for me in this one. Which is funny, since I didn't track all the setups as meticulously as I normally do.