Of all the superhero series currently running on mainstream television, Supergirl is probably the one that hews most closely to some semblance of reality. That's not to say that it's not as "out there" as Agents of S.H.I.E.L.D. (with which it shares the plot elements of secret government agencies and omnipresent alien invasion) or the rest of the CW DC series (from which it is one dimension removed), but it's hard to deny that Supergirl probably spends more "downtime" in its characters lives away from comic book heroics than anything else in the genre.
Part of that is likely the leftover DNA from the series original conception as part of the CBS lineup, which frames Supergirl's first season as a more traditional Millennial "working-girl" series where the complicated part of the heroine's mandatory complicated personal life was that she was also Supergirl. As such, the show has at its foundation an episode-to-episode formula wherein character relationships and long-term personal storylines take precedence over supervillain shenanigans - which are typically presented either as B-stories or as the inciting incidents that call personal/character issues into the forefront (see: the most recent episode, "Alex," where a villain kidnapping/imprisoning Alex Danvers is mainly an opportunity to exacerbate and then resolve issues between Kara and Maggie Sawyer).
Season 2 has leaned more heavily into the offbeat side of its setup, having moved to the same network (though not the same universe - it's complicated) as the broader DCEU "Arrowverse," but the normal-ness of Kara's world relative to the world of the presumed audience has remained a fixed-point in its development. That's to be expected, but the most notable long-term effect on the series proper likely wasn't: In being the Arrowverse production that lives closest to reality in terms of worldbuilding, Supergirl has come to grapple most directly with topical subject matter... effectively making it the most politically-charged superhero show on broadcast television.
To be sure, there aren't a lot of contenders for that title: The rest of the Arrowverse shows are more concerned with their own respective mythos than matters that touch reality, while Agents of S.H.I.E.L.D. - despite being about a government surveillance agency - has only opted to stake out a newsworthy ideological bent in it's recent season 4 HYDRA-centric alternate-universe story (though they've made up for lost time in having a villain growl about "Making HYDRA great again!" to drive the metaphor home). But that's all still far and removed from Supergirl, which built much its first season around Kara and Cat Grant eyeing each other uneasily across the ideological gulf between Millennial and Boomer/Gen-X feminism and centered season 2 on the immigration-allegory of Supergirl's origin story and her conflict with an anti-alien hate group that parallels the rise of anti-immigrant White Nationalism in the U.S. and Europe.
Now, with the announcement of the title of season 2's final episode, Supergirl has once again signaled that it has no intention of backing off this particular distinction. As revealed late Monday night, the hotly-anticipated seasonal sendoff will be titled "Nevertheless, She Persisted" - a reference to a derisive criticism leveled at U.S. Senator Elizabeth Warren by a male colleague that became a political flashpoint earlier this year. Warren, who had been speaking against the controversial nomination of Jefferson Beauregard Sessions III to the post of Attorney General by President Donald Trump, had begun to read from a letter warning against Sessions' record on race relations from a previous nomination authored by Coretta Scott King (the widow of Civil Rights leader Martin Luther King) only to be interrupted by a vote to silence her; with Republican Mitch McConnell describing the situation in dry terms:
“Senator Warren was giving a lengthy speech. She had appeared to violate the rule. She was warned. She was given an explanation. Nevertheless, she persisted.”
The quote became a viral hashtag phenomenon almost immediately, initially in support of Warren's protestation but growing to encompass support for women in politics more broadly. In March, Chelsea Clinton (daughter of former Secretary of State and presidential candidate Hillary Clinton) announced that she would author a children's book about female accomplishment throughout history with "She Persisted" as its title.
It would probably be pushing it to assume that "borrowing" the now-iconic quote for its finale title is meant to indicate anything about the actual plot of Supergirl's Season 2 sendoff - whatever is about to go down between Kara Zor-El, The D.E.O., Queen Rhea, Lena Luthor and (maybe?) Lillian Luthor and CADMUS probably bears little resemblance to a Senate vote for or against an Attorney General nominee, and it's likely that Supergirl is co-opting the title mainly as a reference to Kara overcoming some yet to be revealed hardship to fight another day as a "hat-tip" to the series' studiously-maintained feminist bonafides.
But that doing so is seen (clearly) as a priority for the series can only strengthen indications that Supergirl is planning to own its (not so secret) identity as the socially-conscious superhero series even more strongly as it heads into Season 3. And considering it wasn't too long ago that how - if at all - the show would adjust to the era of Donald Trump (considering that one of its main plotlines was clearly drafted as a preemptive parallel to the presumed eventuality of a very different U.S. President) felt like an open question; that should make the future very interesting indeed.