With Supergirl currently airing its sixth and final season, it can be hard to remember just how much the show has changed since it started. Before switching to the CW and officially becoming a part of the Arrowverse, Supergirl's first season aired on CBS, with the president of the CW having passed on it for fear it was one DC project too many. However, after CBS decided to drop it, the CW brought it on board, and slowly made it part of the Arrowverse (originally as another universe, with crossover events).
While the show and its hero Kara (Melissa Benoist) have evolved a lot since its early days, with beloved characters like Lena Luthor, Nia, and Brainy all being introduced in later seasons, there are some parts of Supergirl that remain unique to its first. In fact, in some ways season 1 had a far more contained narrative than it does today.
Lucy Lane
Lois Lane's little sister, Lucy Lane (Jenna Dewan) is introduced to Supergirl as James Olsen's (Mehcad Brooks) ex, working for her father in the legal branch of the US Army. Although her initial relationship with Kara is strained, the two become close, particularly after Kara reveals her secret identity in episode 17. "Manhunter".
Although she only appears in season 1, Lucy has a full character arc, both with James, and professionally as she goes from working for her father to Cat after the two bond over a wish to see more women in positions of power in episode "Childish Things". Her later journey to co-director of the DEO is satisfying to watch unfold.
Jeremiah Danvers Mystery
At the start of Supergirl, Kara's adoptive father Jeremiah Danvers (Dean Cain) is presumed dead after he'd vanished 10 years earlier. As the season progresses, however, it is revealed that Jeremiah is alive (in "Manhunter"), and being held captive by Project Cadmus.
These secrets run through the storylines of both J'onn J'onzz (David Harewood) and Alex Danvers (Chyler Leigh) over the course of the season, as the two try to uncover where Jeremiah is, and what led to his capture. It's a storyline with high emotional stakes, with episode 17 seeing the pair go on the run in order to find him.
Off-screen Superman
Though the Arrowverse's Clark Kent (Tyler Hoechlin) makes his on-screen debut in Supergirl's second season (and now has a show of his own, Superman & Lois), the hero remains an off-screen presence in season 1, where Kara communicates with him online only.
It is fun to see the Kryptonians in action together, but Superman's absence in the show's earliest season gives Kara the room to become her own hero, and later becomes important to the plot when the whole human population (and Clark!) fall pray to Myriad's trance in the season's penultimate episode, "Myriad", a moment that exemplifies the cousins differences.
Astra
Twin to Kara's mother, Astra In-Ze (Laura Benanti) serves as one of season 1's main antagonists. As retaliation for her imprisonment on Fort Rozz, she hopes to rule over the Earth alongside her husband Non (Chris Vance).
Astra acts as Kara's main tie to Krypton in this season, and provides a way for her to feel connected to her home planet. Caught between her aunt and her adoptive family, some of season 1's best moments come from Kara's reaction to Astra's death in "For The Girl Who Has Everything". Not to mention, one of Supergirl's best fight scenes occurs when Kara and her aunt face off in "Hostile Takeover".
Hank's Big Reveal
Though now known as J'onn J'onzz, the Martian Manhunter was disguising himself as Hank Henshaw at the start of Supergirl's run. With so much of the first season centering on identity, J'onn's hiding acted as a parallel to Kara's own secrets.
When it's initially revealed to the audience at the end of the second episode that Hank is an alien, his intentions remain unclear. As J'onn's story is disclosed, though, with the heartbreaking scenes of his family's death in "Strange Visitor From Another Planet", it becomes apparent that he is hiding only as a way to protect himself, kickstarting the storyline of how the DEO reacts to aliens.
Kara & Alex Rescue Each Other
To kickstart Kara's adventure on the way to becoming Supergirl, she is forced to use her powers in order to rescue Alex from a plane about to crash in the show's pilot. In a parallel moment in the season's final episode, Alex flies Kara's old pod to rescue her sister in outer space.
These two moments bookend season 1, outlining the most important dynamic of the show, and the love shared between the Danvers sisters despite their differences. It's the season's focus on the pair, particularly in episodes like "For The Girl Who Has Everything", where Alex pulls Kara from a dangerous dream of Krypton, that make it worthy of revisiting time and again.
Kara Is Human For A Day
Having become somewhat reliant on her powers, Kara is forced to live as a human in episode 7, "Human For A Day", after burning herself out and temporarily losing her abilities. It affects all aspects of her life, from her day job at CatCo to her ability to catch a cold.
Most importantly though, Kara losing her powers gives her the opportunity to prove that they are not what makes her a hero. In a tense scene, a very vulnerable Kara is able to de-escalate a robbery in progress, all without the safety of her bulletproof skin.
The Flash Crossover
Between them they have some of the Arrowverse's best superhero catchphrases, but when Kara meets Barry Allen (Grant Gustin) in "Worlds Finest", the two are more interested in geeking out about each other's abilities than giving grand speeches.
A great episode for a number of reasons, being able to meet another hero (that she's not related to!) gives Kara the chance to relate to someone who understands her position without judgment, whilst giving her someone to test her powers against, in a fan-favorite scene where the two race one another. Additionally, it brings Kara to the multiverse, setting up her integration into the Arrowverse.
Assistant Kara
Her heroics may take up a lot of her time, but Kara also has an important day job. As assistant to Cat Grant (Calista Flockhart), Kara has to attend to the CEO's particular needs, whilst ensuring that her perceptive boss doesn't figure out what she's hiding.
The dynamic between Cat and Kara accounts for some of the shows funniest scenes, with Kara using her powers to anticipate Cat's wishes in the pilot a prime example. The job also gives Kara something to focus on outside of just being Supergirl, where she is able to pursue other passions that don't involve her cape, and remain a part of the people she is fighting to protect.
Cat Grant
With a strict demeanor that nonetheless gives way to make her part of some of Supergirl's best heartwarming scenes, Cat Grant was a pivotal part of season 1. Not only did she give Kara a way to stay connected to her civilian life, but she also gave Supergirl her name.
Cat's presence on Supergirl gives Kara a mentor to advise her on issues big or small. Whether visiting Cat as her assistant or as Supergirl, Cat becomes a confidant that is able to guide her when she begins to doubt her abilities, culminating in the promotion Cat gives her in the season finale. Unfortunately, Cat Grant was cut out of the series when it was moved to the CW.