Taking the story out of the present day to the past of two of the main protagonists who just so happened to be mildly awful as children is a risky move. Without risk there’s no reward, which is especially true in storytelling. Unfortunately, sometimes that risk doesn’t pay off. “Midvale” is a pretty solid example of that.
Kara and Alex Danvers were quintessential teenage girls in out of the ordinary circumstances. Before Kara fell to Earth, both girls had families. This causes some understandable tension between the two teenage girls, but the death of a friend brings them together. Their investigation of the death of Kenny Lee foreshadows their futures as a DEO Agent and Supergirl, but not in a way that’s worth writing home about.
The episode could have benefitted from making the murder mystery aspect interesting, but it’s exactly as predictable as you’d expect. They even toss in a “they killed Kenny” joke for terrible measure, but at least we get to watch the jerk quarterback get shoved into a locker as payback. Knocking the quarterback around is one of several times Kara uses her power as a teen, and the F.B.I isn’t happy about it. Only it’s not the F.B.I, it’s J’onn in disguise as an agent who looks exactly like Alura Zor-El, which was a real weird scene with good intentions.
Kara leaves her interaction with Not-Mom-Or-FBI-But-Really-J’onn prepared to give up her powers for good. Or, at least for a solid hour or two. Alex finds herself in trouble when she finds the true murderer in Kenny’s case and ends up looking down the barrel of a revolver. The Kryptonian saves her new-found sister, and the two bridge the gap between their different worlds.
All of this is used to connect from the moment that Alex is drunk and angry at Kara for trying to get her to talk about her problems (which is a reasonable frustration), and the two of them being okay in the morning. Kara’s refusal to acknowledge that her humanity makes her the hero she is is still a present theme in Supergirl, and her talk with Eliza seemed to do very little to shake her from her resolve. When they’re little, she tells Alex that she’d rather be human than risk losing her, though. Hopefully we’ll see that come into play later, and not have Mon-El’s return be the cause of her change of heart.