He supported Donald Trump. She supported Hillary Clinton.

But in the midst of the 2016 election, Brian D. Sicknick, an officer with the U.S. Capitol Police, and Caroline Behringer, an adviser for a liberal congresswoman, found common ground.

They met mornings at an entrance to the Capitol, she heading to her office, he protecting those doing the people’s work. They chatted about unwinding in the outdoors and joked about being on opposite sides of the political divide tearing the nation apart.