Hello! It's been a long time, but I'm back with a Danvers Sisters one-shot (that'll definitely be longer than a one-shot)! This is a re-write/extension of the end scene of 4x10 with Kara and Alex. Big thanks to Anna for the prompt!

"I can't."

Kara's voice, soft as breath, lands square against Alex's stomach like a fist. The feeling sinks deep into her gut as Kara slips past and leaves the door swinging behind her. A gust upends a swirl of dust in its wake.

Alex's eyes flicker between J'onn and the fleeting form of her sister, before Alex pushes herself off the table. "I'll be back," she promises and J'onn gives her a nod, his own brows creasing. The pain from each sister radiates, battering at his psyche in waves. He watches Alex leave the room, then turns away, toward books and files that commemorate the past. That remind of history's formative nature.

The hallway is ice cold and vacant when Alex enters, but the sound of hyperventilating turns her head toward the right, leading her feet to a corridor of office doors and Kara, with her eyes closed and her face crumpling and tears streaming down her cheeks.

Alex drops beside her. Never mind the hard of the ground or the chill of tile against her jeans, she slides into place until her hip is pressed against Kara's, and without a word, Kara turns into Alex's arms, grappling for something to fill her hands.

"Kara," Alex whispers, and her lips brush against blonde hair, her arms accepting the trembling body and leaping shoulders that crash into her own. "Just breathe for a second, for me."

She threads her fingers through Kara's hair and runs her touch slowly through the loose waves, as her other hand sprawls across Kara's back and holds her close.

"I'm not going anywhere until I know you're going to be okay."

Kara hiccups and fights with air. It isn't until Alex leans back and slips her arms around Kara's shoulder, linking onto her watery blue eyes, that Kara lets go of the breath coiled inside her.

"It's like you're dying, Alex," Kara murmurs, drops her head and tries to study the hem of her jeans through the blurriness clouding her eyes.

"But I'm not," Alex promises. She reaches out and tucks a strand of hair behind Kara's ear.

"But you're leaving, and—and you promised that you wouldn't." Her voice cracks and she retracts her hand from Alex's, shoving at the tears on her cheeks before bringing the loose fist against her lips and tilting to make herself small.

"I'm doing this so you can still be you," Alex says and the weight of a sob throbs in her throat. "So you can be Kara Danvers."

Kara shakes her head, sending hair bouncing across her face and clinging to her damp cheeks. She swipes it away and looks at her sister, reclaims the hand she let go. "I'm Kara Zor-El… The Danvers—the best parts about me on this planet—that's all from you. I'm sorry," Kara whispers. "I know you don't want this either—I know it's just as hard for you, I just—How could I ever be a Danvers without you?"

"I'll still be here," Alex tries to reassure, but her words ride on tears and after a beat of taut silence they're collapsing into each other and crying.

"It's like I'm losing my whole world again," Kara says and holds Alex tight. "But it's worse this time, because I won't have a sister. I won't have you, waiting for me on the other side of the Phantom Zone and the nightmares and all the times I couldn't breathe."

"I'll always be there for you, Kara, no matter what the form. No memories, or lack thereof, are going to change the fact that I love you with everything I have and that I would do anything—anything—to keep you safe, even when it breaks my heart."

Kara brushes at Alex's tears with her thumb. "I love you, Alex."

Alex captures Kara's hand on her cheek and squeezes it. "I love you, too, Kara. I wish there were a better way."

Kara straightens. "We could kill her and hide the body?"

A laugh, watery and full of air, flees from Alex's lungs. "We could. But we shouldn't."

"I know." Kara deflates with a sigh, slumping against Alex, their backs lean against the wall while their shoulders press together. "I could fly her to the fortress of solitude or—or drop her off in Antarctica? Or J'onn could wipe her memory way back and we could leave her on some island in the middle of the ocean where people have barely even heard of Supergirl? Or—"

"Kara." Alex settles a hand above Kara's knee and gives a light squeeze. "Maybe there's a way to make this reversible, and we can undo it all when you're safe again and Colonel Haley, but there are no guarantees that that'll even happen and we have to go through with this, I would never forgive myself if something happened to you."

Kara's lip quivers as she keeps her gaze locked on Alex. "You're the best thing that's ever happened to me, Alex. Even if I hate your morals and logic right now."

Alex pulls a sad smile across her lips before sighing and interlacing their hands.

"I'll be there, when it happens." Kara bites her lip, leaving an indent against the soft pink. "If you want me too, I'll be there. I'll hold your hand the whole time."

Alex shakes her head, the weight of tears seeping back into her words. "If I'm looking at you, I won't ever be able to tell J'onn to do it."

"Are you sure?" Kara examines her through watery eyes.

Alex nods. "But, Kara? You're going to need someone to get through this. Someone who's shown you again and again that she's on your side, no matter what."

"Do you…" Kara furrows her brow, lifting her head from Alex's shoulder. "Are you talking about Lena?"

Alex nods.

"But she doesn't know?"

"I wouldn't be so sure that she hasn't put the pieces together, Kar, that girl's basically got degrees into double digits. Just make sure she stays far from the DEO."

Kara lets a laugh slip through the lump in her throat. "What if she doesn't know and telling her ruins everything?"

Alex shakes her head. "I don't think it will. She's your best friend. She loves you too much."

"And what if I lose both of you?" Kara's voice cracks.

"Never, Kara." Alex cups her hands around Kara's warm, damp cheeks. "You are never losing me."

"Can we wait one more minute before you go in?" Kara asks, her heart a weight in her chest too heavy for even Supergirl to lift. "I just need to hug you and remember as much as I can, it might not be like this again."

"Of course," Alex whispers and pulls Kara close, their tears running together. In just a few moments this memory won't exist. She holds on tight and doesn't know how she'll ever let go.