1. Tarlok is Amon.
At the end of the last episode many exclaim the way Tarlok approached Korra after he knocked her out is similar to the way Amon approached Korra in earlier episodes. Also, the fact that Tarlok is “doing exactly what Amon says benders are doing” seems to be too…perfect. What I came up with is that Tarlok is Amon and is using fear in order to give himself more power. He plays up what Amon does and then switches back in order to take advantage of the situation. Also, my brother thinks that the Blood Bending ability is somehow possibly tied to Amon being able to take away a bender’s abilities. No one has any idea how Amon is able to do this in the first place, so it’s an open debate.
2. Tarlok and Amon are working together.
Amon had this grand idea that Tarlok vehemently opposed in principle but decided to go along with. Tarlok would essentially find a way for Amon to get what he wanted, while Tarlok would seem to be an extremist in going after the Equalists. This is all supported by the evidence above for the Tarlok is Amon theory. It seems like Tarlok is perfectly playing into Amon’s hands and things are going well for Amon. Although obviously at one point in the story they would simply double cross each other. The question is, who will be enough steps ahead in the game?