At the same time, her online life was taking a sharp, pro-Russia turn. In 2017, on Twitter, she had shown support for the special counsel’s investigation into Russian interference in the 2016 presidential election. By late 2018, she was inveighing against “anti-Russian propaganda” in America.

“Why would a liberal Democrat support Vladimir Vladimirovich Putin?” she wrote in an essay on Medium. “Maybe it is because I believe he has saved the world from a large conflict on more than one occasion.”…

She told visitors about a Russian man with whom she was video-chatting online.

The relationship was active when she made her first public accusations of harassment against Mr. Biden, according to two women who saw photos of the man, whom they took to be a love interest. Neither could recall his name. The relationship lasted through the summer, recalled one of the women, who would speak only on the condition of anonymity.

“She had a picture of a guy and said that they had been communicating,” recalled the other woman, Rachel Sabajo, a former housemate of Ms. Reade who confessed to developing a personal aversion to her. “I said, ‘Why Russia?’ And she said, ‘Putin is so dreamy, I really get him.’”

Ms. Reade denied having a romantic relationship with anyone in Russia, saying her online activity was part of her book research.