Getting back into the OR without Richard knowing requires everyone to lie for Derek, but they can't keep the secret for long. Richard is about to storm in and demand Derek stop, but we can't believe it when Arizona, of all people (we know she has problems standing up to authority figures!) tells him, "You do not get to go in there and be a bully. not on my watch." We're so proud of her!
And we're so proud of Derek, who manages not only to remove the tumor, but to avoid paralyzing Isaac in the process, which had seemed unavoidable. The next day, Derek tells the Chief he hopes they can put this episode behind them. We're not at all prepared for what Richard says next: "you're fired. immediately. get the hell out of my hospital." Instead of taking him at his word, however, the newly zen Derek simply repeats Isaac's advice and tells the chief. "Go home. Sleep on it. We'll talk more tomorrow."