Supergirl, Season 4

Kara:
Supergirl would never work with Lex.

Lena:
It's not Supergirl. She's a blank slate. Or, at least she was.

Kara:
What are you saying?

Lena:
It's a question of nature versus nurture. She's been tested, trained, and indoctrinated by Lex in a prison in one of the most oppressive regimes in the world.

Kara:
But she has to have good in her.

Lena:
There was good in Sam. And Reign was a monster. Lex has created the very thing he fears the most. A Kryptonian weapon trained as a killer. And in Lex's hands, it's more dangerous than an atomic bomb. And he has it pointed right at America.

Kara:
She is not an "it". Lex may have molded her, but there has to be some part of Supergirl still in her.