The series does become darker as it progresses, as the new character introduced in the story just threw the whole moral dynamic up on its head. Also the relationship between our casts is starting to get strained as personal doubts starts to build among them and the nature of our heroes' capabilities and their role in the setting is called into question. It's an ominous setup for what is coming soon, definitely this is building up to something. The show is still going strong at this juncture, hope it doesn't stop there.