Michael Ellis is acknowledged, by conservatives and moderates, to be a smart, young lawyer. Yet his quick rise from the House Intelligence Committee to the legal staff of the National Security Council and then to senior intelligence posts has puzzled many of the same people. After serving as senior director for intelligence at the National Security Council, Mr. Ellis was appointed this week to be general counsel of the National Security Agency, one of the most influential legal posts in the intelligence community. Mr. Ellis was chosen after the White House put pressure on the Pentagon. Because it is a Civil Service position, Mr. Ellis would continue in the job into the next administration. Although the Biden White House could order his removal, he would be difficult to fire, and would have to be given another legal job in the Defense Department.