The link on that page for Miller looked at his high school days and beyond. He was clearly troubled already then.
I was reminded of that by this new piece from the New Yorker which looks at how he leads the extreme and cruel immigration policies.
"One participant in the November meeting pointed out that El Salvador didn’t have a functioning asylum system. “They don’t need a system,” Miller interrupted. He began speaking over people, asking questions, then cutting off the answers.
As the meeting ended, Miller held up his hand to make a final comment. “I didn’t mean to come across as harsh,” he said. His voice dropped. “It’s just that this is all I care about. I don’t have a family. I don’t have anything else. This is my life.”
Miller, who is thirty-four, with thinning hair and a sharp, narrow face, is an anomaly in Washington: an adviser with total authority over a single issue that has come to define an entire Administration. “We have never had a President who ran, and won, on immigration,” Muzaffar Chishti, of the Migration Policy Institute, told me. “And he’s kept his promise on immigration.” Miller, who was a speechwriter during the campaign, is now Trump’s longest-serving senior aide. He is also an Internet meme, a public scourge, and a catch-all symbol of the racism and malice of the current government. In a cast of exceptionally polarizing officials, he has embraced the role of archvillain."
"He asked to head the Domestic Policy Council, an influential but amorphous group inside the White House. The position gave him proximity to the President and insulation from congressional scrutiny; he would issue, rather than implement, orders. “The rest of us have to testify before Congress. That’s a check. If you’re going to have your ass hauled before Congress, you’re not going to feel comfortable breaking the law,” a former top Administration official told me. 'Miller will never have to testify for anything.'”
"In the days leading up to Trump’s Inauguration, Miller and a close associate named Gene Hamilton, another former Sessions staffer in his mid-thirties, drafted an executive order called “Protecting the Nation from Foreign Terrorist Entry Into the United States”—the travel ban.
When Trump signed it, none of the top officials at the Department of Homeland Security, which was in charge of enforcing the ban, had been notified in advance. Travellers with valid visas were suddenly trapped at American airports, unable to enter the country; refugees who, after years of waiting, had been vetted and approved for entry were turned back. Thousands of protesters and civil-rights attorneys began congregating at airports across the country, and Senators Graham and McCain issued a statement saying that “we should not turn our backs on those refugees who . . . pose no demonstrable threat to our nation, and who have suffered unspeakable horrors.” Jared Kushner, the President’s son-in-law and senior adviser, was enraged. The next day, when the President’s senior staff assembled in the Situation Room, Miller told John Kelly, the head of D.H.S.; Tom Bossert, the President’s homeland-security adviser; and officials from the State Department, “This is the new world order. You need to get on board,” according to an account in “Border Wars,” by Julie Hirschfeld Davis and Michael D. Shear."
While many of Trump's appointees have either seen themselves as people who could hold Trump back, or people just happy to be able to put their Trump service on their resumes, Miller is one who clearly has Trump's ear and pushes Trump towards his worst decisions on immigration.