Sieg meets Jack. All of them.
The eighteenth episode of Fate Apocrypha open with the final moments of the last episode from Atalanta’s perspective after she put an arrow into both Jack and her Master. She’s not happy with killing a child. More so when said child explodes into fog and a bunch of other children appear with a haunting gaze as they ask “why she killed their mother” and effectively screwing with her mind.
Then she wakes and has a memory of her time with Medea (Caster from the Fate Stay Night series) in her Lily form. We then get some backstory on why Atalanta likes children, since she was saved as one by Artemis. Then Jack appears and basically tries to guilt her into staying with them.
Sieg is next on the mind whammy train as he’s forced to see humanity among its worse when he witnesses a woman get assaulted and then run over by a horse carriage. Jack appears then to tell him bluntly that humanity is crap and he’s a fool for believing otherwise, punctuated by people and corpses being thrown into the river. This brings him to his knees and threatens to break him, even as Astolfo goes to find him.
Jeanne figures out its a dream from the past of Assassin of the Black and then proceeds to not care before vowing to defeat her as Sieg has words with the memory of the woman who tried to kill him last episode. She basically tells him the world is broken and that they need a miracle to change the system. Then more memories of Jack invade him before Ruler basically states that she intends to exorcise them since she can’t save them. They’re already a part of Jack’s legend, so there’s no getting around that.
Atalanta, however, disagrees and interferes to defend them. There’s some back and forth before the souls that make up Jack decide to go with the whole exorcism deal since its better than suffering eternally. Atalanta can only watch as it happens and then proceeds to snap since she believed they deserved to be saved and that the Holy Grail could do it. Chiron and Astolfo drive her off, but not before she swears vengeance on them all.
That leaves Ruler to try and calm down Sieg. She can’t say humans are innocent and doesn’t try to. She only ask that he doesn’t give up on humanity before the sun rises over the city once more. The episode ends with Sieg narrating how he thought the world was beautiful before then and Hell would always reside in him.
Oh, and Shakespeare breaks the fourth wall to state we’re nearing the end.
So, this episode was divided between Jack assaulting everyone mentally with the nightmare of her past and defining what is good or evil. You see, this incarnation of Jack the Ripper is an amalgamation of several thousand children turned into evil spirits that can only bring misery to those who tried to comfort them. London back then was really bad place, due to a lot of factors, and Jack was born from it then. Here’s a video to summarize it:
Moving on, we then get to see how the other characters react to that situation. Sieg, being painfully naive since he was born less than a month ago, gets hit the hardest since he can relate to it. His kind were born and then thrown away, so he relates to it and realizes that magi are the only assholes when Jack put him through the discount version of the cursed grail mud.
Ruler, on the other hand, has been through this before. She was executed by some of the worst of humanity, with some people looking on and cheering as the execution happened. She knows that people are cruel at times, just like Shirou Amakusa, only that she just can’t bring herself to hate them.
That being said, she doesn’t consider herself some innocent saint. She never called herself one since she fought on the battlefield, even if she didn’t wield a sword, and did so by her own choice. She’s covered in just as much blood as the soldiers she commanded and so she won’t hesitate to kill an enemy before her if she cannot save them, even if those people were victims.
Atalanta outright snapped when exposed to it, having been thrown out as a child for being born a girl. There was no goddess to save those children like her, so she seeks a miracle to do so and thus wants the Holy Grail. The fact that Jeanne put them down only served to make her an earnest enemy instead of just being part of a rival faction.
So, now we enter the final stretch of the series. The lines are drawn and everyone has their motivations, so we can only look at how the battle between the two Saints and Sieg draws to a close.