Author's Note: Hey guys! I've been completely in love with season 3 and had an idea about episode 1. It's not going to be a happy one, just warning you now. It is actually my first fan fiction ever and I'm pretty nervous to see if you guys like it but hopefully you do! I realize it's a little bold to write a tragedy for my first fanfic but I'm just going to dive right in! Hope you guys like it :)

Warning: Major Character Death

Disclaimer: All rights belong to the CW. I do not own Supergirl.

Kara had seen the missile fire. She knew immediately what she had to do. She thought of all the people at the waterfront in danger; Alex, Maggie, Lena, and so many more. As soon as she saw it fire, she was off without a moment's hesitation.

She was aware that Alex had been calling her name out of concern, but that didn't matter now. The only thing that really mattered was keeping everyone safe. Kara was running out of breath and she realized that she would probably not make it out of this one alive. But nevertheless, she put on a brave face, and headed towards the missile with a steely determination.

As she neared it, she heard a click of some sort. And knew immediately that it meant bad news. A trigger of some kind. An explosion. Supergirl realized what she had to do. She did her best to wrap around it and shield it with her body to decrease the potential damage. Then it detonated.

She was vaguely aware of the submarine exploding in the background, falling victim to the huge blast. But she couldn't focus on it too much with her whole body screaming in pain. Kara was out of oxygen and she felt excruciating pain. Everywhere. And it was then that Supergirl truly realized the gravity of the situation. She was dying.

Kara could faintly hear her big sister calling for her through the comms. But there was nothing she could do. Nothing she could say. Alex was worlds away. But she wasn't sad or regretful, just grateful for everything Alex had done for her. Grateful that she finally had the chance to repay her debt by saving her life, and everyone else's as well. With these peaceful thoughts swirling through her mind, she finally succumbed to the darkness, her last thoughts of Alex and hoping she would still be able to live a happy life with Maggie.

Up on the waterfront, after feeling the ground shake and the ensuing anxiety it caused, Alex was panicking. She had called Kara's name for at least two minutes straight. No response. Maggie was beside herself with worry. After all, Kara had become like a little sister to her too. They stood, eyes intently focused on the water. Hoping for a sign of life. A bright red cape. Maybe even just a flash of blonde hair. But nothing came.

A good five more minutes had passed and Alex knew that even Supergirl, with all her powers and strength, couldn't hold her breath for this long. She realized with a sinking feeling that Kara had saved the city at the expense of her own life. Saved Maggie. Saved her. Alex cursed her little sister for her continued determination and selflessness, because all she wanted was for Kara to be safe. And those two things had ended her life.

Alex's heart split in two when she finally realized that she had seen Kara for the last time. A single tear fell down her face. Maggie quietly sobbed off to the side, National City with her too. Mourning the loss of their great hero. Supergirl. Their protector. But Alex's pain ran so much deeper. Because this was her sister. Their lives had been connected. Their hearts. Their souls.

The city may have been mourning for Supergirl, but Alex was mourning for Kara Danvers.

She realized she would never get to see her baby sister's vibrant face ever again. Her inner strength. Her kind smile. Her excited laugh. Her capacity for forgiveness and compassion.

She knew everything would be different now. And all she could feel was deep pain. Sharp, piercing pain.

Everyone around her watched silently. With sympathy. With sadness.

It was at that moment they all realized: when Kara had died, a part of Alex had died with her.

Alex was broken and for this, there was no fix. Everyone could see it.

And it was completely and utterly heartbreaking.

THE END

Thank you guys so much for reading! Please review! I want to know what you guys thought about my first ever fic. Any criticism or comments are welcome! Please don't hesitate to send in any prompts you guys want me to write or try out. I'm very excited to be joining this community and want to know what you guys want to see and read.

I love you all and hope you all have a blessed day! Until next time :)