'Supergirl' spoilers! Milly Alcock explains that 'twisted' ending

Spoiler alert! The following post discusses important plot points and the ending of “Supergirl” (in theaters now) so beware if you haven’t seen it yet.

There are certain secrets “Supergirl” director Craig Gillespie wants to keep.

For example, when the question comes up if a certain weird little alien on a space bus who sounds unmistakably like Seth Rogen is actually Rogen.

“He's your friend, so you can do what you want,” “Supergirl" star Milly Alcock says in an interview with director Craig Gillespie, who grins and responds that “it sounded remarkably like him, didn’t it?”

“I thought it was you,” Alcock quips.

“Yeah, Seth sounds a lot like me,” Gillespie adds.

So that will remain a mystery for now. But there’s definitely more to talk about with “Supergirl,” especially in terms of character choices. Kara Zor-El (Alcock) goes on a planet-hopping mission to save her beloved Krypto – with young and vengeful girl Ruthye (Eve Ridley) in tow – after he’s poisoned by the villainous Krem of the Yellow Hills (Matthias Schoenaerts).

Alcock and Gillespie discuss a fateful decision that Kara makes in the DC superhero movie as well as her changing dynamic with her cousin Clark Kent, aka Superman (David Corenswet).

What happens in the ending of ‘Supergirl’?

With some assistance from the bounty hunter Lobo (Jason Momoa), Kara and Ruthye track down Krem and his evil Brigands. Kara defeats Krem in a fight to get the antidote for Krypto, and Ruthye wants to kill him herself since he murdered her parents. Kara talks her out of it, and when Ruthye walks away, Kara turns back to Krem and stabs him multiple times with a sword.

“For me, it was kind of the only choice,” Alcock tells USA TODAY. “She's protecting Ruthye from becoming even further traumatized in having to deal with all of these massive, conflicting emotions, and she's trying to teach her how to not do as she does, basically. Not to run away from all the pain and know that that pain has to be fixed internally, as opposed to externally through drinking or hurting people or hurting yourself.”

Alcock adds that Kara’s choice is also “what separates her from Clark," who had a similar confrontation with Lex Luthor (Nicholas Hoult) at the end of “Superman” but, outside of a mini-mauling by Krypto, let the authorities handle him.

“It's the right thing to do in this twisted way. She’s seen so many people suffer.”

Gillespie adds that that moment is Kara “owning her version of what a superhero is. You see that conflict between her and Clark and the way they argue about this, and Clark has a very different perspective.”

Does ‘Supergirl’ have a post-credits scene?

Unlike last summer’s “Superman,” “Supergirl” doesn’t have anything after the final scene. But it is a significant one: Kara reunites with Clark on Earth, and unlike the flashback earlier in the film where she seems uncertain there, it looks like she might be sticking around. Fans won’t have to wait too long to see her again either, since director James Gunn has said she’ll have “a big role” in the 2027 “Superman” sequel “Man of Tomorrow.”

Alcock says her dynamic with Corenswet is pretty simple: “I am Kara, David is Clark,” she laughs. While their belief systems create “this very natural fraction,” the fact is they’re family.

“There's still a requirement and a capacity to love and to empathize," Alcock figures, "and to kind of allow the other person to win – not even win an argument, but you know what you do with the people that you love? Sometimes you walk away, even though you know that you're right or you let them win when you know that you should have."

“There's that really beautiful messy nuance within it. And I really hope that we get to explore that a bit more.”