
There's a reason Kathleen wasn't in The Last of Us Video Game
To complicate the morality of the story, the series introduces a new character. The character does the opposite.

This season of The Last of Us, which is Neil Druckmann and Craig Mazin's adaptation of the 2013 videogame has shown near perfect fidelity to the source material. The Last of Us is a video game adaptation that has been faithfully adapted from the game's screenplay. It also features sequences that were filmed and edited to match multiple cutscenes. Perhaps ever.(Ignoring Halo’s attempts to recreate fist-person shooting gameplay.
This season's deviations have mostly been about rounding out peripheral characters. Episode 3 will tell the story of Bill and Frank, who only appear briefly during the events of the videogame.
Mazin and Druckmann discussed the decision this week on The Last of Us Podcast. Druckmann explained what Kathleen's character allows for the series to accomplish: "The show gives us the opportunity to leave Joel, Ellie, and flesh out other characters. The Last of Us can do the best thing: flesh out your antagonist to show that they have a motivation for doing what they are doing.
Mazin compared Kathleen with Madame Defarge in A Tale Of Two Cities to highlight the writer's choice for moral ambiguity.(Defarge is both a revolutionary as well as an antagonist in Dickens’ novel. Druckmann says this about the type of character: "They don’t see themselves as villains and/or bad guys." Because our goals overlap, but are different, we are at odds with one another.
We meet a group of militarized civilians, the "hunters", in the 2013 videogame. We don't learn anything about their motivations or leadership structure. It's assumed that they successfully challenged government control after the outbreak. That's all. They are presented mostly as goons that Joel and Ellie will dispatch on their journey through Pittsburgh.
Kathleen is the leader of the group. These events take place in Kansas City. Although she does not appear in the videogame, her position is assumed. Someone must be leading the hunters.
Kathleen, however, appears to be the antagonist. Her presence introduces a type of villainy that the video game rarely avoids. Evil appears in times of despair. Joel and Ellie meet along a rode and act out of self-preservation. Like many apocalyptic stories, tension is found in trust. Although the player does kill many hunters, they are never portrayed as moral men. Some levels can be achieved without killing the hunters. The game forces the player make that moral decision. Joel is acting only out of self-preservation, which makes it more problematic than for the hunters.
The show is ironically moving closer to binaries (rights and wrongs) by introducing Kathleen than the relativism they want her character to reflect. Kathleen is a pure antagonist, not Joel the begging boy who must be killed when he reaches Kansas City. This scene more than humanizes hunters. Although she may have her motives, they don't change our judgments of her actions or alter our view of who we should root for.