Lena Luthor

===Medusa===
[[File:Kara questioned Lena about her mother.png|thumb|left|250px|Kara questioning Lena about her mother.]]
Right after Thanksgiving (featuring a space-time breach that momentarily tore open over the dining table at Kara's place), Kara, Alex and their friends went back to the D.E.O. where they discussed what to do with Cadmus, now aware of Lillian's role in its chain of command. Though she finds it unlikely that Lena could provide any knowledge on Lillian beyond familial matters, Kara eagerly volunteered to investigate L-Corp herself on behalf of the agency. She insists that her civilian guise as a reporter — and her so-called ''“sneakiness”'' — was enough to gather intel from Lena. She asks her agency colleagues to stave off their usual cloak-and-dagger methods of discreetly gathering information (i.e. bugging phones, hacking company records, etc.). Unbeknownst to Kara, Alex has Winn prepare such underhanded methods anyway, telling him to have them ready soon after Kara left.

When Kara comes to L-Corp asking Lena about her mother, the latter says they did not have a very good relationship and often disagreed. However, Lena notices that Kara was trying to glean information on Lillian through her, and after Kara's departure, Lena calls her mother and says they need to talk. As Lillian comes, the two of them exchanged some snide comments — about the holiday and how more open to each other their family used to be when both Lionel and Lex were still with them together in their collective lives — before Lena tells her that a reporter is investigating about her, and asks if she's hiding something. Lillian knows at once that the reporter in question was none other than her former Kryptonian captive but instead says that she has no idea. Lena realizes that her mother is lying.

Later [[Hank Henshaw|Cyborg Superman]] comes to L-Corp, in an attempt to steal a rare synthetic substance that [[Project Cadmus|Cadmus]] needed to spread the [[Medusa Virus]], but Supergirl arrives and a fight between the two ensued. Lena comes to the site of their fight and, noticing her, the cyborg throws her the detached 'L' of the company's scaled-up three-dimensional logo. Kara manages to cover her and asks her to leave. After a while Kara returns to Lena's office in the guise of Supergirl and Lena graciously thanks her for saving her life, then Supergirl reveals to her that her mother runs Cadmus. Hurt, Lena refuses to believe it, accusing the superheroine to be no different than anyone who readily condemns the Luthors' disposition and morality because of their family name, and asks Supergirl to leave. Before she does, Kara imparted a few inspiring words to the CEO, that she honestly believes Lena to be a better person than anyone else in the Luthor family. She tells Lena she must shine through as her own hero if she were to ever get out of Lex and Lillian's villainous shadow, and that got Lena thinking.

Later, Lena organizes another meeting with her mother at L-Corp and confesses she knows Lillian runs Cadmus. Lillian makes no effort to refute the allegation. Then, she was told that if she wanted Lena's help, all Lillian had to do was ask for it. Lena gives Lillian a case containing Isotope 454, the substance exclusively manufactured by L-Corp, that Cadmus needed to initiate the Medusa Virus into a city-wide outbreak effect. Lillian was surprised at Lena's sudden, out-of-the-blue willingness; Lena tells her that perhaps it was time for Lillian to get to know her daughter better.

[[File:Lillian betrayed by Lena and arrested.png|thumb|250px|Lena betrays Lillian and gets her arrested.]]
They then left for the National City port, where they intend to release the virus with a rocket launcher. Lillian, as a means to test her daughter's loyalty to Cadmus, gives Lena the key to activate it. Just as she is about to do it, [[J'onn J'onzz|Martian Manhunter]] and Supergirl arrive to stop her, having been alerted by their agency's sensors of the Isotope 454 portion, provided by Lena to her mother, being moved from L-Corp to where the Luthor women now are. Supergirl attempts to talk Lena out of releasing the virus but the latter seemingly conforms to her tainted family legacy, remarking that she is "a Luthor," and launches the rocket. Supergirl flies after it while Martian Manhunter confronts Lillian and Lena, and forcibly battles Cyborg Superman who interfered to prevent the Luthors from being apprehended. Lillian makes the rocket explode before Supergirl could act, spreading the virus across the sky. However, none of the aliens in the city were affected. Lillian realizes that Lena substituted the isotope for one that would instead render the virus inert. Lena condescendingly confesses and reveals that she also called the police, who were coming to arrest Lillian. After that, Lena presumably provided the D.E.O with an unaltered sample of Medusa, which was crucial in finally curing J'onn of his condition of becoming a White Martian after a blood transfusion from one.<ref name="Medusa" />