According exclusively to TVLine Lucy Lane, who’s Lois Lane’s younger sister, will be introduced in episode 3 of season 1 of Supergirl, as a recurring character.
The character is described to be in her mid-20s to early 30s, brash, funny and beautiful as her sister Lois, yet strong, smart and successful in her own right. She is also an ex-girlfriend to Jimmy Olsen, much like she’s also in the comics.
TVLine speculate that there’ll be a love triangle, because in the pilot episode Kara showed she had a crush on Jimmy and with Lucy around, there might be some lingering feelings between them that’ll get in the way for Kara.
They also speculate there might be a Superwoman storyline, as Lucy Lane in the comics became Superwoman at one point and became a major problem for Supergirl during the story’s run, as Lucy Lane as Superwoman was anti-Supergirl.