One thing I will always appreciate Fullmetal Alchemist for is the fact that they let Roy Mustang be complicit in genocide.
Mustang is an Atoner figure. Something that plagues Atoner figures is when writers are too precious about the characters we're meant to like to actually let them be guilty of something serious.
The Atoner might be trying to make amends for their involvement in the Great '87 Hotel Massacre, and then three seasons in you find out what happened. And it's like, "I drove a taxi to the hotel, and the KILLER was in it! I ferried the killer to the hotel! That makes me responsible, and now I must atone for being nearby while the killings took place! And also vanquish the real killer who is the villain for this season."
Or maybe the Atoner did do the killings but they were under mind control the whole time and would never, ever have done it in their right mind.
But FMA said no. Mustang, Hawkeye, Hughes, even Armstrong to an extent though he suffered a breakdown and fled during it. They did that shit. They followed their orders and they did that shit. And it haunts them.
Roy did that shit. And his atonement, his grand ambition, is to see everyone responsible for that shit brought to justice for their crimes. Including himself.
That is how you write an atonement plot.
