Disclaimer: I do not own Supergirl or the characters.
A/N: This was written for a prompt from Caroline1929
When Alex entered the warehouse she saw Supergirl in a sealed chamber banging on the clear sides, trying to escape. Approaching the chamber she saw fear in Kara's eyes before seeing green gas fill the chamber from the bottom.
"Kara!" Alex cried banging on the unbreakable sides of the chamber.
"Alex. It's Kryptonite. I can't escape."
"Hold on. We'll get you out." Alex said.
"I love you." Kara said, trying to be brave. Not wanting Alex to see how terrified she was as the green gas rose higher as her strength decreased.
"Kara, you need to hold on. We are getting you out of there." Alex said putting her palm up against the clear barrier, a motion matched by Kara.
"Please don't blame yourself." Kara pleaded as nausea and dizziness set in and she sunk to her knees. Alex's hand following Kara's down the chamber wall.
"Kara." Alex said, tears flowing freely. "Please Kara, don't give up. We're going to get you out. Don't give up. I need you so much." Alex said as the gas filled Kara's lungs and she began to cough.
"I'm sorry," Kara spluttered before eventually adding, "for everything."
"No Kara, you have nothing to be sorry for." Alex said mortified her dying sister felt the need to apologise. Before she could say anything more the Kryptonite gas took hold in Kara's lungs and Alex was helpless to do anything other than watch as Kara choked for every poisoned breath before finally falling unconscious.
"Stand back." J'onn ordered rushing into the warehouse before firing the acoustic weapon at the chamber. The vibrations it created causing the chamber walls to shatter. Throwing the weapon down he picked Kara up in his arms and flew the unconscious, not breathing, hero back to the DEO.
-00-
When J'onn returned to the warehouse five minutes later Alex was on the floor staring blankly at the broken chamber from where green gas still flowed.
"Alex." He called softly as she approached her.
"Is she-" Alex started unable to finish the question.
"She's alive." J'onn said before adding grimly. "Barely. But she is holding on. Let's take you to her."
Nodding Alex climbed to her feet and let J'onn fly her to the DEO.
When they arrived Alex was directed to the decontamination room, banned from seeing Kara until all traces of Kryptonite had been washed from her and her clothes.
As she scrubbed and scrubbed she couldn't banish the images of Kara in pain from her mind. The images causing her to mindlessly scrub her skin raw as she thought of all the ways she had let her sister down.
When she finally stumbled into the infirmary she saw her sister, no longer a figure of strength and happiness, but a weak, pale body, hooked up to a mask and surrounded by lamps. Kara's wheezing the loudest noise in the room.
"She hasn't woken yet." Winn said from where he sat by Kara's side. "But she's fighting for every breath. That's a good thing right? I mean she is fighting, really fighting. She isn't giving up." He added, clearly shaken at seeing his friend so fragile.
"Yes." Alex said numbly, hating the sound of Kara's wheezing. "Fighting is good. And Kara is a fighter."
"I'll give you some space." Winn said sensing Alex needed time alone with her sister. "If I can do anything just ask."
"Thanks." Alex said before sitting next to Kara.
"Kara, please wake up." Alex pleaded as she gripped her sister's hand. "You said you didn't want to be abandoned again and I get that because I don't want to be abandoned either. Please Kara I need you to wake up. I can't do this without you. You are the sun, you give life and joy to everyone around you. I need that. Without you I would have lost myself to the darkness and if you leave me now I don't think I will escape the void." She went on as tears ran down her face. "I love you Kara and I need my sister. Please don't give up. Keep fighting. I know you are in a bad place right now and I know giving up must seem attractive, but I need you. Maybe I'm being selfish, but please Kara, even if you never do anything for me again, fight. I know you can do this because you are the strongest person I know. And I know it seems like the universe is against you and it is one battle after another. But in-between those fights there are good times. I know I haven't been around as much as I should, but I promise if, no when, you pull through I am going to be round so much you will get sick of the sight of me."
When she felt Kara's fingers twitch in her hand she squeezed her sister's hand harder.
"I'm right here. I will always be here. Keep fighting." Alex said using her spare hand to stroke a stray hair off Kara's forehead. When she saw Kara's eyes flutter open revealing pain and despair she leaned in closer and said.
"It'll get better. Keep fighting. The Kryptonite is almost gone. When it is gone you will be back to normal. I know I can't help you fight it off, but I am right here for you. Okay?" She asked as Kara nodded her head slightly as tears of pain ran down her cheeks.
"Do you remember when you were fourteen and we raced along the beach. I told you I was fine, but I wasn't. I didn't want to admit I couldn't keep up so I ran harder and faster than I had ever done. Then after a couple of miles I collapsed. I couldn't breathe, every breath hurt. But you held me, called me a stupid, stubborn, human, and talked to me until I could draw a steady breath? I wish I could remember what you said. Because if I could do that for you right now I would. I wish I could be as strong for you as you have always been for me. Even though I am not as strong as you I am right here and I am not going anywhere. I will be with you as long as it takes for you to breathe freely again." Alex said as Kara's breathing became less laboured.
"You are doing great Kara. Just keeping fighting one breath at time." She encouraged as the last of the Kryptonite left her sister's system. As Kara's breathing continued to get easier Alex said. "Just rest. You'll feel better when you wake up. And I'll be right here."
-00-
"Al-" Kara croaked sometime later causing Alex's head to snap upright.
"Kara? How are you feeling?" She asked.
"'Kay. Thirsty." Kara said, her voice hoarse.
"Suck on these." Alex said giving Kara some ice chips. "All the Kryptonite is gone. You should start feeling better soon."
"Already feeling better with you here." Kara said as the ice chips soothed her throat.
"I'm not going anywhere." Alex promised her as Kara started to sit up, causing Alex to ask. "What are you doing?"
"I'm okay." Kara assured her. "But I need a hug."
Without hesitation Alex wrapped her arms round her little sister before confessing. "I thought I'd lost you."
"I thought you'd lost me." Kara said returning the hug before asking. "Did you develop superpowers?"
"No. Why?"
"This is quite some hug."
"Sorry am I hurting you?" Alex asked trying to pull away, only for Kara to hold her tightly.
"No. This is just what I need." Kara replied.
-00-
"Okay, so I have potstickers and pizza. Ice cream is in the freezer and there are crullers for later." Alex said putting the food down on the table in front of Kara who was wrapped in a blanket on her couch.
"You didn't have to do all this." Kara said.
"Maybe. But I wanted to." Alex said sitting next to Kara who lifted the blanket it and placed it over Alex. "I was so scared I was going to lose you."
"Takes more than a little green gas to get rid of me." Kara said trying to sound brave and unaffected.
Knowing better Alex pulled Kara in for a hug. After several minutes Alex said.
"I don't understand why you said that."
"Said what?" Kara asked.
"That you were sorry. You were dying. I had failed to protect you. Why were you apologising? It was my fault."
"It wasn't your fault." Kara argued. "I walked into the trap. You warned me against going in."
"My job is to protect you. I failed."
"No you didn't. I'm alive." Kara reminded her.
"Why were you apologising?" Alex asked.
"For disrupting your life. For not being as good a sister to you as you are to me." Kara said.
"Kara you are the best sister on the planet, in fact in the galaxy."
"Based on your sample of two planets?" Kara asked amused.
"Based on the fact I know in my heart there is no better sister than you." Alex said holding Kara a little tighter.
"You might want to look in the mirror." Kara said. "And as someone who has been to more than two planets, my opinion counts more."
"You wish." Alex replied.
"Perhaps we should just agree that the Danvers sisters are the strongest force out there." Kara said.
"That I can agree with." Alex said kissing Kara's head as she continued to hold her sister.
-The End
A/N: Thanks for reading and reviewing. I hope you enjoyed it.