I do not own Supergirl. All I own is Christi and those you do not recognise.

This is a plot that I couldn't get out of my head and it wouldn't stop bothering me so here it is. If there are any spelling errors or such do PM me.

----------

Christi Emerson. That was the name she took when she had landed on Earth, over twenty-four years ago, to the day. When she had arrived, oh so long ago, Christi was surprised no one had noticed, nor came for her. See, she had been observing the planet and it's tendencies to capture aliens. When no one came, she played it off as dumb luck and carried on, waiting. Christi had a history with Kara Zor-El and her family. She used to visit Kara's mother, Alura, and often found Kara studying different planets and species. One time Kara had come up to her asking about her planet and species, knowing full well that Christi wasn't a Kryptonian. Christi's race had died out long ago, drawn into a massive war that destroyed everyone and everything she had ever known. Her planet was gone, name forgotten except in some of the eldest books held within few planets. Christi was an Elrizan, from the planet Elrizia.

Elrizia was one of the most powerful world's alongside Krypton. A land with silver trees and red grass that seemed to catch fire when the sun and moon crossed paths. Unlike other planets, when the moon and sun crossed it didn't become an eclipse, the moon became transparent. Yet it dulled the sun enough for the sky to become night, but with a shining light among the stars. The silver trees lit the stars of the night and seemed to shower sparks of light onto the fiery ground and into the sky. And the world itself looked to grow transparent, and disappear. It was always an amazing event when this happened. Many people from neighboring planets came to see the splendor of the Elrizan home world on such a wondrous night.

Despite their powerful reputation, the people of Elrizia were one of the most peaceful people out there. The wisdom of their long lives, and noble nature helped them solve many disputes without the galaxy. But then a group rose up from within Elrizia, wanting command, control, and overall domination everywhere. A war began and soon friends fought friends, families turned on one another, and nowhere was safe.

For a long time the war raged on, and Christi never knew about it having been on Krypton the entire time. (Few Elrizans had ever left their home planet because they preferred the quiet life. Obviously, Christi was one of those who left, as she loved the stars and wanted to travel.) No one on Elrizia was able to send a message for help and as a result, the planet destroyed itself. Billions of lives lost, an entire race destroyed. All Elrizans gone. All but one, at least. Christi had only found out when she tried to go home. Alura's ancestors had been the one to break the news to her, having been one of the few people who knew Christi the best. The last being Kara and Alura.

Kara had been so interested in Christi's planet and she wanted to ask more about it but Christi had to leave, and she wouldn't be back for a long time. During that time the Kryptonian home world became unstable. Months went by and Christi knew this world would die just as hers had. So she went back to Krypton - the same day Kara's mother had summoned her, an urgent request. Alura had instructed her to look after Kara mere days before the planet had gone up in flames. Alura had met with Jor-El and they had to decide the destination that Kara and Kal-El would use. Once decided Christi left immediately to Earth, a strange planet she had studied, and waited for Kal-El and Kara Zor-El to join her. When only Kal-El had shown she had grown worried. Kara was supposed to be right behind him.

Christi waited, and waited, and waited. Despite all of the time it took for Kara to get to Earth, Christi spent her time watching over Kal-El, now known as Clark Kent, and to the world, as Superman, or the Man of Steel. For years she moved around to not draw any attention to herself because she aged so slowly in Earth's atmosphere. Even slower than a Kryptonian, her DNA having already granted her a long life - like the rest of her species. She kept an eye on Hank Henshaw whenever he came around. The Department of Extranormal Operations, or DEO, didn't need to be in her business. She had accidentally found out about them when she had studied Earth.

Finally, after many years, Kara Zor-El had arrived and was still thirteen years old. Christi had no idea why, her guess being the Phantom Zone, or a wormhole displacement, but she was glad Kara got to Earth safely. And Kara grew up never knowing she had a guardian watching over her or her new family. Christi knew she was in good hands and stayed close by.

Twelve years after Kara arrived, Christi lived in National City and worked at CatCo Worldwide Media, keeping her word and looking after Kara. If she hadn't taken the job it would have been weird for her to hang around when she didn't even work there. Christi worked a few desks over from Kara but could see her perfectly. Christi became friends with Kara only a week after she joined, which was a few months after Supergirl had shown up. Being friends with Kara also lead her to be friends with Winn, and later on James Olsen. It wasn't so bad working at CatCo. As long as you weren't the one being called to Ms. Grants office.

On a normal day Christi would rarely answer calls, write emails, and overhear Kara talking to Winn about some crises she needed to deal with. But on other days, if you were lucky enough, you could see Supergirl fly around the city. Never once had Christi ever used her abilities, as she never needed to. But she kept training herself in case she was ever needed. The humans had two heroes now. Why would they need a third? That's where this story begins.