Since her debut in 1959’s Action Comics #252, Supergirl has been reinvented time and again. Originally a teen girl riff on Superboy, Supergirl has been everything from a modern woman making her way through 1970s Chicago to a shapeshifting blob of goo to a scantily-clad minion of Darkseid. Even outside of comics, we’ve seen varying interpretations of the character, with Milly Alcock’s hard-scrabble hero playing very differently from the wholesome do-gooders played by Helen Slater and Melissa Benoist.

The most significant difference between Supergirls might involve one we’ll never see. While promoting the new movie, directed by Craig Gillespie, screenwriter Ana Nogueira has credited the film’s success to a script she wrote about the Supergirl that Sasha Calle played in The Flash. “It was useful to me,” Noguiera told Entertainment Weekly of the script. “There is a real thing when you’re doing this, you have to really onboard yourself on things like power set, what these characters are capable of, what a fight would look like, how strong you want them to be … So that was really useful, that I knew that power set for [Supergirl] in and out.”

While the two Supergirls do have similar power sets, they have very little else in common. Where the current movie draws inspiration from the Tom King and Bilquis Evely miniseries Supergirl: Woman of Tomorrow, the previous iteration would have borrowed from the New 52 Supergirl and the Flashpoint depiction of Superman.

The Flashpoint connection makes sense, as 2023’s The Flash adapted that comic book storyline, which itself led to a line-wide reboot of DC Comics. Set in the DCEU that began with Zack Snyder‘s Man of Steel, The Flash sees Barry Allen (Ezra Miller) going back in time to prevent the murder of his mother. When he tries to return to his own time, Barry gets knocked off course and arrives in an alternate 2013, one in which there’s no Superman to prevent General Zod’s attack on Earth.

The two Flashes get help first from a retired Bruce Wayne, played once again by Michael Keaton. Together, the trio learns about a Kryptonian ship that crashed in Siberia. They track down the ship, thinking it belongs to Superman, but instead find Supergirl, who has been kept hidden in a research facility and tested upon since her arrival.

The idea of Supergirl being used as a test subject comes from 2011’s Project Superman #1, which told the story of Kal-El in the darker world that the comic book Barry Allen created when he went back in time in Flashpoint. At the end of the Flashpoint storyline, Barry puts things right when he goes back to the present. But he gets some things wrong, leading to the DC Universe reboot known as the New 52. With the reboot, the Project Superman story was more or less transformed to Supergirl, making Kara a darker and more angry character, who did not trust humanity.

The Supergirl of The Flash contained aspects of those stories. At first, Kara resented humanity for the way she treated her, and saw no reason to save them. But upon Barry’s urging, Kara found her more heroic side and joined the fight against Zod. Originally, the film would have ended with scenes setting up future movies with Calle’s Supergirl and Keaton’s aged Batman, with the former getting her own solo film written by Nogueira.

To this day, Nogueira says very little about that movie, telling Entertainment Weekly, “I don’t think I can even say what it was about, but it could not have been more different.” Presumably, however, we can guess that it would have followed the trajectory of the New 52 Superman comics. Those stories tracked Kara’s slow and circuitous route toward heroism, as she rejects the way of her cousin and finds her own path. The comic book version of this Supergirl sometimes did things her cousin would never consider, such as joining the rage-filled Red Lantern Corps. But she did the right thing more often than not.

Certainly, we can see some echoes of that Supergirl in the version played by Milly Alcock. While she’s never as antagonistic toward humanity as the New 52 character, this Supergirl has to find out how to be good in her own way, and ultimately finds a code that’s very different from the one held by Superman.

Would that Supergirl movie be better than the one now playing in theaters? There’s no way of knowing, but we can say with confidence that whether she’s a party girl trying to find her home or an alien making peace with a planet that mistreated her, she’ll always be Supergirl.

Supergirl is now playing in theaters worldwide.

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