Here is a little reboot of Siderea (Siderel-Zal). It mainly is little changes on her appearance and the way she arrived to Earth.
Long time ago...
As we all know, the planet Krypton was destroyed, and its, theoretically, only survivor came to Earth to become the greatest heroe of all time, Kal-El.
Later it was learned that a city of Krypton, Argo City, broke away from the explosion, surviving as an asteroid. Argo City was the site of origin of Kara Zor-El, better known as Supergirl.
Well, they were not the only survivors. A small island of Krypton broke away from the explosion as well. On this island was the city of Ximalion. A city thriving in young scientific minds, every day innovating on the technology of the planet. But Ximalion wasn't as lucky as Argo City. The Ximalion asteroid was going towards two black holes, and the radioactivity of the exposed rocks was affecting all citizens, making them steriles generation after generation. Some centuries later, no one could procreate. The last baby born, was a girl called Siderel-Zal, and there were just five persons living in Ximalion.
Now Siderel is a very intelligent girl. She studied all researches she could from archives, from the historicals Jor-El's documents to her parents' attempts for saving Ximalion from its fate, near those two black holes. But now she was the last one. Her old teacher and she herself were the last citizens alive, and he died a couple of weeks ago. Siderel didn't find the way for saving the city from its fate, but she thinks she has get the way of going out from that "prison". Using all the knowledge that she could get in her life, she built some kind of ship. In theory, it could make her travel anywhere in the known universe. She was sure she had discovered where the Jor-El's ship, mentioned in historical records, had been headed. She was not going to lose anything by trying it. She knew staying in Ximalion she will going to die alone, but if she goes out in that ship... who knows? She also knows that the proximity of the two black holes distorts the time continuity, but what she doesn't know is if it was going to be a journey to the future, or to the past...
The Earth: Present day
Clark was walking in the middle of the night, thoughtfully. He left Lois at her appartment half an hour ago. What should he do? Tell Lois all the truth? Will she get mad? He can't hide his truth from her more time, anyway, they are starting something serious...
Suddenly all city was dark, seemed like a blackout, and then that red flare crossed the sky over the buildings. For instinct he started to take off his suit, "another work for Superman" he thought for himself, and then he stopped. That thing wasn't falling, it took a curve and came towards his position, landing inside a building.
Clark doubted and waited. From the building a strong red light came out with some smoke, and from the smoke, somebody appeared, flying. Seemed a woman, and apparently she wasn't hostil, for now. Clark opened wide his eyes, that emblem on her suit, it was kryptonian, but he didn't recognize the house it belongs. Then the woman talked to him through her helmet, she also seemed surprised:
- I can't believe I did it, you.. you must be Jor-El's son... my ship detected something kryptonian when landing... I can't believe it, I did it... How...? Where... when I am? You are Kal-El, aren't you?
Clark was stunned:
- But who are you?... - Superman stopped for listening something - Somebody is coming, we need to talk, but not here. Follow me...