These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ryan in a sense, since he starts killing people just for wanting to leave the city when it becomes obvious it's a lost cause that he's unwilling to believe. There's also the fact that unlike Fontaine, he more then willing to kidnap girls from their families to become Little Sisters, such as the case when he stares at Bill's daughter after an encounter with a Big Daddy.
Cavendish, since it's implied that he actually kidnaps one of the girls to become a little sister. He likewise is shown to be racist and all too eager to shoot Bill and his family after they're cornered at the lighthouse entrance.
Tenenbaum having rough sex with Frank. She's basically asking him to simulate raping her because she can't stand being touched any other way.
Sander Cohen and his infamous act of forcing a youth to screw an octopus at a wild party.
They Wasted a Perfectly Good Plot: To a degree considering just how many stories the novel tries to contain and share. Because of the book's rushed state to incorporate lore from BioShock 2, many notable characters from that game have a diminished presence. There's also several off-page events, be they due to being in-game materials (such as Audio Diary events) or simply not being portrayed on the page.
The Woobie: Bill McDonagh and his family. Even moreso in how they manage to escape, but he does not.