When Vanya arrived in Dallas on October 12, 1963, she stumbled through a street and got hit by a car driven by Sissy (Marin Ireland), one of several new characters this season.
Vanya, who had no memories of what happened before landing in Texas, was taken in by Sissy and her husband, Carl (Stephen Bogaert), and became a nanny to their autistic son named Harlan (Justin Paul Kelly).
During episode four, Harlan drowned in a pond, but Vanya used her powers to bring him back to life. In doing so, she inadvertently gave Harlan some of her powers, which played a part in the finale.
Vanya also formed a romantic relationship with Sissy, which was a step up from the murderer named Leonard Peabody (John Magaro) who was her love interest during season one. Vanya and Sissy's relationship had complications because the latter character was in a loveless marriage with Carl and because homophobia was still rampant in the '60s.
Carl was also one of the second season's antagonists. He was furious after learning that Vanya and Sissy fell in love and threatened to send Harlan to an institution if Vanya didn't pack her things and leave their farm.
After seeing Vanya use her powers on the highway patrol, Carl felt threatened and accused her of being a KGB agent. On episode nine, Carl fired a rifle at Sissy and Vanya, but Harlan used his powers and redirected the bullet to his father, killing him.
With Carl dead, Sissy and Harlan were free to leave Dallas and have a better life, possibly in California. Vanya hoped that they would follow her when she escaped 1963, but Sissy worried that they wouldn't be able to have a normal life and Harlan would be in danger. So, they said goodbye and Sissy asked Vanya to come back to her if she ever found a safe way to do so.
Vanya's powers predictably played a key role in the end of the world in 1963. Diego accessed the Commission's footage from the Infinite Switchroom and found out that her powers made an FBI building explode, which resulted in the Soviets attacking the US, leading to nuclear war.
By episode eight, it seemed like that would actually happen to Vanya, as she was being interrogated and tortured (via LSD) by a special agent from the FBI who suspected that she was a Communist and threat to the US.
The Hargreeves' mission then became trying to stop Vanya from causing the federal building to explode. They succeeded with the help of Ben, who was able to reach Vanya's mind, get through to her, and prevent the explosion from happening (more on that later).