android654 wrote...
Sarah wasn't going to kill him until he threatened Chuck. Niket was appolegetic and even promised to say nothing. Sarah has an emotional response, Miranda has a calculated response.
Both are calculated responses.
Sarah did not kill him simply because he made some empty threat like "Once I get out, I'll kill your boyfriend.". Chuck's life is threatened almost every day but Sarah does not kill every villain in the show.
Sarah killed him because he knew that Chuck was the Intersect and she knew (after the beating she gave the villain) Fulcrum would never stop until they rescued that particular agent who would then let the leaders of Fulcrum know the truth about Chuck.
Thus, by killing this agent, she is eliminating a potential threat to Chuck.
This is not different from Miranda killing Niket to eliminate a potential threat to Oriana. Niket only promised to say nothing after Shepard stopped Miranda from shooting him. Up until that point, Niket was unapologetic, even accusing Miranda and questioning her motives for taking Oriana.
After Niket's promise, Miranda was willing to let him go.