[Kon very carefully doesn't flinch. Back home, everyone knows, but everyone is not Kryptonian. It's different telling her. Not that he'll keep it from her because what would be the point?]

I'm half Kryptonian. [He could leave it there and let Kara assume he's Kal's son. It's the logical assumption. He doesn't though.

It's a struggle but he manages to look her in the eyes as he speaks, voice and posture deceptively laid back as if he's talking about the weather.]

See, the government got all freaked out by the idea of Superman one day dying and leaving them without their golden superhero and they figured it'd be good to have a backup on hand. And bam, there's my very short and not so compelling origin story.