The Man in Black
He's traveled to the blood arroyo with Lawrence to figure out the next level of the game, but he can't find where the snake lays its eggs until he walks down to the water and sees that outlaw Girl With the Dragon Snake Tattoo topless in the water. After murdering a few of her outlaw crew to create some job openings, the Man in Black volunteers himself and Lawrence for the task of getting their outlaw boss Hector out of jail in exchange for the backstory of the tattoo.
During this exchange, he asks Snake Tattoo if she's heard of Arnold, basically "the original settler of these parts," and talks about how Arnold had created a world where "you could do anything you want except one thing: you can't die." But then, the MiB says, Arnold broke his own rule by dying in the park, which is crappy, because he had one more story to tell -- a story with "real stakes, real violence." And he shows her the scalp maze again and says her tattoos are the second part of the puzzle. She's like, "I didn't realize we were going to get into such an intensely deep conversation, but if you'd like to get Hector out of jail, that's cool."
Also that night, as he sits around a campfire, a guest comes up to the MiB and says he's a giant fan of his, which shouldn't be a surprise because Ed Harris is terrific in The Rock, but actually the guest was referring to the MiB's work outside of Westworld, and mentions that his foundation literally saved his sister's life.
The MIB cuts him off and threatens him and tells him he's on vacation, but still this further deepens the MiB backstory. Is he some sort of good samaritan after all? Does this make the William the White Hat is the Man in Black theory all the stronger? After all, if William married into Logan's family, which owns a piece of the park (further helping to explain why, for the most part, the staff leaves the Man in Black alone), William could have incredible wealth outside said park and be using it for real-life white-hat purposes.
The MiB and Lawrence somehow find themselves in a prison stagecoach where the MiB tells Lawrence he's "always been a prisoner" and "What if I told you I'm here to set you free?" because being set free is a big theme in this episode. Lawrence probably thinks he's being literal because Lawrence's narrative seems to always involve him being actually being in jail. Anyway, the jail decides to shoot Lawrence in front of a shooting squad, but the Man in Black uses some sort of exploding cigars to blow himself and the outlaw Hector out of jail and kill everyone in the shooting squad just as Lawrence was going to get dead for the second time. "Motherfucker," Lawrence says. Indeed, Lawrence. Indeed.
Girl with Snake Tattoo then tells her backstory. Her whole family and village were brutally murdered by "masked men." She had to put her mother's blood on her body so they'd think she was dead, and so when she tracked down each of them, she used her blood to paint her skin again. And she only has one person left to find, so she can paint the head of the snake on her face and truly look like Mike Tyson: "He has many names," she says. "Most know him as Wyatt."
The Man in Black smiles. And goes off with Lawrence looking for Wyatt. When they do, they stumble across someone tied up naked like Jesus. It's poor Teddy. "Put me out of my misery," Teddy asks. "That's not really how this park works," the Man in Black tells him, sort of, and goes off in search of more donors to his foundation.