Alien Hero of Metropolis.

An unknown gem

We see a book as it opened to reveal the story about the diamonds.

Voice: Once upon a time, the Gem Homeworld was ruled by Diamonds: White, Yellow, Blue, Pink, and the littlest Diamond even littler than Pink, Black. While the other Diamonds conquered many worlds across the galaxy, Pink and Black had only one - the planet Earth. One day, Pink and Black fled the comforts of Homeworld. On Earth, they made a new home, new friends, and finally, new lives; giving up her form to bequeath her gem to her half-human son and black had to infuse his energy to create a new being. Without Pink and Black, Gemkind entered an era of despair. But, when Steven Universe learned of his heritage and (Y/N) (L/N) learned of his origin, they reunited with their fellow Diamonds and championed a new era of peace and freedom across the furthest reaches of space.

Then the book was closed shut as we see White Diamond as she was holding the book.

White Diamond: And now, dear Gems everywhere, I'm pleased to announce that Steven and (Y/N) are both finally ready to take their rightful places on Black Diamond And Pink Diamond's thrones! Roll the cameras!

We then see the gems of the hour. Steven Universe and (Y/N) (L/N)

Steven and (Y/N): How's it going, everybody? *Flashes charming smiles*

Steven: I know you all might be thinking of me and (Y/N)  as the new Pink Diamond and Black Diamond, but you don't have to put us on thrones. We already have a rightful place, and it's on Earth.

(Y/N): Yeah, you don't have to do this for us.

The diamonds that were on the thrones then leaned forward in surprise.

Blue Diamond: Huh?

White Diamond: What?

Steven: It's a beach house, where I live with my friends, Garnet, Amethyst, and Pearl.

(Y/N): And I live in a town called Metropolis with my friends Babs, Jessica, Zee, Karen, Kara, and Diana.

Steven: As much as we've loved dismantling the empire and saving all your planets, we can't wait to get home and spend some quality time with our friends.

As you both finished your message White Diamond look a bit annoyed.

White Diamond: Cut the feed.

Yellow Pearl: Yes my diamond! *turns off the cameras*

The diamonds: What do you mean you're not staying?!

(Y/N): We're saying is that our home is on Earth, I understand that you all missed pink and black.

White Diamond: (Y/N), Steven please.

Yellow Diamond: You can't go.

Blue Diamond: We need you! Or at least I do.

Steven: Thanks but no thanks.

(Y/N): But Blue if you want you can come with us to see how progress is going at little homeworld.

Blue Diamond: That sounds fair.

(Y/N): Thank you.

Steven: And white I understand you missed pink and you miss black diamond a lot.

White Diamond: *blushes* I do miss him very much.

(Y/N): *wink* So guys shall we? *points to the warp pad*

Then you, Steven, and Blue diamond stepped on the warp pad as Blue Diamond made her the same size as you. Then you all were warped back to earth at Steven's house at a glass done at the back of his house as Connie, Diana, Jessica, Kara, Babs, Zee, and Karen were waiting for you along with Desiree and Rebecca (seeing as how we haven't seen them in a while)