Special counsel Robert Mueller faces a unique challenge in his investigation of Russian influence during the 2016 election. In addition to gathering information and prosecuting criminals, he has had to avoid getting fired by his resentful, mercurial, and unscrupulous commander in chief.

Fifteen months into the investigation, he appears to have done a masterful job. By manipulating and distracting Donald Trump and his team of lawyers, he has not only preserved his job, he has maintained complete autonomy and seeded a cluster of spinoff investigations that will be nearly impossible for the White House to stifle. And despite Trump’s insistence that he’s “totally allowed” to intervene whenever he chooses, he won’t dare make a move this close to the midterm election, which means Mueller’s investigation will be protected for at least three more months.

How has he done it?