Just like in the games, Ellie is extremely wary of David when she offers a trade, but she accepts the offer to get antibiotics for Joel. After all, Ellie isn’t naive in understanding that humans are more dangerous than the infected, given that they are capable of committing hypocrisy and disgusting acts in the name of survival. David’s group is no different: Although the show implies that not everyone in the group is aware of his cannibalistic side, these people have no choice but to actively support or passively suffer for David’s abusive behavior. Hypocrisy grips humanity even in a dying world, as David’s group sees Joel as a monster for defending Ellie in college, but fails to acknowledge (or purposefully avoid) their own evils.
While David’s men are determined to kill Ellie, David obsessively insists that he be allowed to live as he can be taken into their group. Frankly, it’s not an act of compassion, it’s part of the twisted power play, because David sees it as an object that will further legitimize the illusion of truth. After Ellie retaliates, she initially intends to kill and eat him, but then continues to play a sick cat-and-mouse game and tries to sexually abuse her. As David’s cannibalistic and pedophilic impulses are mapped so much more clearly in the series, this amplifies the moment when Ellie attacks David multiple times while she’s covered in blood and the room around her is on fire.
Just like in games, David is not the focus, but on Ellie’s anger, trauma, and the cathartic revenge that comes with this act of self-defense. The blood on the lens is a painful reminder that this event will leave its mark on Ellie forever.