Executive Producer Andrew Kreisberg recently sat down with IGN to talk about just how that plan came about, and why they needed a full season under Supergirl's belt before her cousin made his in-person debut.
"I think we've spent a year establishing her, and the year ended triumphantly with her saving the world, so there wasn't any sort of doubt that Supergirl couldn't do it on her own. It felt like you weren't bringing him in to save the day. It was bringing him in the same way that the crossovers with Flash and the Arrow... it becomes about a partnership. It becomes about deepening the characters' relationships, not "Well, Arrow couldn't do it alone!" or "Flash couldn't do it alone!" So that's why it felt right."
Some worry that having Superman (Tyler Hoeclin) on the show will take away from Supergirl (Melissa Benoist), but Kreisberg assured fans that they are embracing that fear head on and that the show's focus is still firmly on Kara.
"When Supergirl and Superman walk into the room, everyone gets really quiet about him. And her reaction is, "Oh, please…" We sort of liken it to if your brother was a famous rock star, or a famous movie star, all you remember is a lifetime of growing up and fighting over who's sitting in the backseat, and sharing a bathroom, and he pulled my hair. And then you go to a restaurant, and people are sending him drinks, like, 'Oh, right this way...' and that's sort of Kara's interaction. People have asked us how do you make sure that Superman doesn't overwhelm the lead of your show? Rather than shy away from that, we're embracing it. It's kind of the idea like, yeah, he is more popular than she is. How does she deal with that? That's our take on that dynamic that's between them."
Supergirl returns to The CW on October 10th.