It's unclear how Becca and Billy met in the show, but in the source material, they first encountered each other while on a train in the UK.
In the show, Becca worked as the senior director of digital marketing at Vought. She was raped by Homelander and forced to go into hiding in a Vought-run neighborhood after giving birth to their son, Ryan, who inherited Homelander's superpowers.
She died during the season two finale after Ryan's lasers accidentally hit her throat during a fight against Stormfront.
In the comics, she was raped by Black Noir under the disguise of Homelander and died during childbirth.