What I love about this scene is how it shows how much Chief cares for Cortana. He’s literally spent the most part of his life following orders from his superiors - doing everything they say, making sure they were content with his work and his outcome. He’s always done his best - not necessarily wanting to please but wanting to get the job done. He was built to follow orders and do his job - taught from a young age that that was the way of life and the only way. But when Cortana’s life comes into the question, those years of sticking to the regulations and saying, “Yes, ma’am/sir” every single time he’s given an order goes out the window. Cortana is more important to him than his whole purpose in life.