The darkest moment in Fullmetal Alchemist has been haunting fans for two decades now, and the reason why makes it pretty easy to see. First debuting in 2001, the popular manga series created by Hiromu Arakawa follows Edward and Alphonse Elric, two brothers who attempt to bring their dead mother back using alchemy. When it backfires though, Edward loses his leg while Alphonse loses his body entirely. Edward manages to salvage his brother's consciousness by giving up his right arm and transfers it into a metallic body, swearing to restore it. While the series would venture into dark places as a conspiracy begins to unfold within their government, one moment in particular has stuck with fans so much that it brings chills mentioning it.
Chapter 5, "The Alchemist's Suffering," follows Edward and Alphonse seeking out a bio-alchemist to see if there's anything in that field to help them restore their bodies. They're directed to a chimera specialist named Shou Tucker, a man who is credited with creating the first talking chimera, which is a creature formed by merging two beings that aren't genetically the same. When they meet him, he's struggling with getting his license renewed and is caring for his young daughter Nina and their dog Alexander. After getting to know them for some time, the brothers return to see that he's created a new chimera...but once it speaks, Edward, horrified, realizes that it's Nina merged with her dog. It ends on a depressing note as they cannot turn her back.
So why has this moment stuck with fans years after it first debuted? The answer lies in its clever writing and use of tone. For starters, this is a chapter that's ripe with foreshadowing. Little clues are thrown throughout the chapter that come back later when Edward realizes what's going on. For example, a chimera they're told about at the beginning lines up with Shou mentioning that his wife "left him." It's revealed later that this chimera is actually the result of a failed experiment where Shou fused his wife with another creature, leading to her death. Upon rereading it, fans can notice that the clues to this reveal were there all along.
On top of this, the drastic shift in tone braces the reader for the horrifying reveal. Before Nina's transformation, the atmosphere is constantly filled with humor. For example, Edward getting jumped on by Alexander is a way for Arakawa to let readers' guards down by alleviating tension. She then pulls the rug out in a drastic cut to the next day when storm clouds are forming and there are more shadows than usual. It all comes to a head at the reveal when the artwork takes on the tone of a horror story. It's so unexpected, but it works.
The biggest reason for this chapter's memorability though is how it establishes Nina and Alexander. They are present throughout, allowing the reader to get to know them and care for them. Nina is an adorable character, and to see her interact with Alphonse and Edward creates a bond with them. Arakawa spends just enough time with them to make them likable, and then she wraps up the arc with the gut punch ending. It's a finale that upsets readers because not only is this a little girl who's been turned into a chimera, this is the little girl readers have come to like. And now she's just...gone.
Fullmetal Alchemist would go on for another nine years before it ultimately concluded, but nothing in the story ever came close to being as much of a horror show as this chapter in the saga. It's dark, depressing and catches the reader off-guard after four chapters of relative levity. Had it not been for Arakawa's clever writing, this could have been a pit stop in the Alchemists' journey, but the development of Nina and the use of foreshadowing elevate it. This is character work at its finest, and it's made this moment in Fullmetal Alchemist the most memorable for dark reasons.