And wow, does Kara Danvers, aka Kara Zor-El, aka Supergirl, love it.
Sure, sure, Alex can take care of herself, but that is NOT COOL.
She tells Winn that Collins was her first collar.

Credit: Katie Yu/The CW
That wouldve made you 17 when you arrested him, Winn says, then realizes.
Yeah, that tracks.
She believes him, particularly when her rigged motorcycle explodes mere moments after she vacates it outside the bar.
Alex being Alex, she insists on setting a trap for the wannabe killer.
This leaves Ruby in the care of Winn, whos…well, hes kind of terrible at first.
The Rubester lashes back that shes not sleeping, either, because its her mom whos become a monster.
And not just any city, but Argo City, Karas hometown.
They borrow cloaks from an open-air market to blend in and such magnificent cloaks these are!
But Kara isnt thrilled that she has to be in disguise even here.
Then Karas overwhelmed to encounter a familiar face: her mother Alura.
(Hes quick to point out that hes just Mr. Mon-El now.)
As such, giving Kara what she seeks will require the High Councils permission.
Kara is thrilled to see a Dar-Essa flower, which used to be in her room as a child.
(We gave her Kryptonian burial rites, Kara assures her mother.)
In fact, many good humans on Earth risk their lives to stop the prisoners of Fort Rozz.
As she speaks, we watch Alex and Jonn spring their trap for the would-be assassin.
As Alura argues, whats the point of Argo Citys survival if it has no soul to save?
Stay on message, lady!
So Lena heads to her lab and reluctantly pumps the kill Kryptonite kill switch.
Then Supergirl and Mon-El crash into the lab with the rock.
Just in time, Reign smirks, breaking free of her cell and moving to punch Supergirl.