When you’re a superhero with a big “S” on your chest, it’s only natural to be suspicious of anybody with the last name “Luthor.” So, when Kara met Lena Luthor in the first half of Supergirl’s second season, there was a lot of doubt over whether or not Lex’s sister had the same villainous streak. Lena proved herself by betraying her super-evil mom, Lillian Luthor, and averting alien genocide, but when Lena returned to Supergirl on Monday’s episode, there’s an ominous hint that there really is an evil seed inside her — because she’s much more of a Luthor than anybody thought.

Lena finds herself in trouble when, thanks to the scheming of her mother and Hank Henshaw, she’s framed for providing Metallo with kryptonite. Now that he’s been recharged — dangerously so, we later learn — Metallo can free Lilian from custody.

Kara strongly believes that Lena was innocent, but pretty much everyone around her thinks Lena was culpable. Perhaps she was playing a long con? Lena seems even more guilty after Metallo breaks her out of prison, kidnapping her so mommy Lillian can take her to Lex’s secret superweapon storehouse. Lillian really just needs Lena’s to get through the lock and gain access to the stockpile (which is full of a bunch of deadly Easter eggs, including the Persuader’s Atomic Axe and a mind-controlling Black Mercy plant).

Lena tries to avoid helping her mother and resists her attempts to turn her as Supergirl saves the day. Although Henshaw and Lillian get away with some weapons despite Supergirl’s best efforts, it’s clear that Lena was innocent. Plus, Metallo explodes and is incredibly dead. Everybody wins, right?

Except, Lena learned a lot about herself during her run-in with her adoptive mother. Lillian drops a bombshell that totally changes Lena’s character — she isn’t any old girl who was adopted into a supervillain family. She’s Lionel Luthor’s daughter from an affair, meaning she’s Lex’s half-sister. Lena truly is a Luthor.

Shortly before the episode closes, we see Lena, having just had an emotional moment with Kara, ponder a chess board. There’s another flashback, and we see a young Lena beating little Lex in chess — which is TV shorthand for letting us know that Lena is actually smarter than her brother. Now that she knows she has a real connection to the Luthor name, should we be worried that Lena is going to break bad?

If Supergirl keeps returning to the “is Lena really good?” plot too much, it’s going to get stale, but Monday’s revelation ups the stakes quite a bit. Plus, it doesn’t look like we’re going to see Lena for a while — next week is all about Kara, Mon-El, and Mr. Mxyzptlk. It’s gonna be totally bonkers, so questions about morality, family, and fate will have to wait until later.

Photos via Warner Bros. Television