AN: Not mine.

Alex has no idea what time it is when she finally stumbles through her front door. She's been at the DEO for nearly thirty-six hours straight, trying desperately to protect J'onn, but finally she couldn't hide her fatigue and exhaustion anymore. After everything that's happened, it's a miracle she made it as long as she did, but finally J'onn told her to go home. He's always been able to tell when she's at her limit.

"They're not going to do anything for the next few days. Go home and get some sleep, Agent Danvers."

"J'onn—"

"That's an order."

Even though he's no longer her boss, it still felt wrong to refuse. So after pressing her hand to the glass one more time, Alex left. Thank god she's had a lot of practice driving dead tired, because otherwise they'd probably be peeling her off the pavement.

Astra is nowhere to be found as Alex enters the dark apartment, but Alex doesn't think much of it. She's probably asleep, the effects of the Kryptonite sword not completely gone yet. Rubbing gritty eyes, Alex chucks her keys on the table. Time for a nice big glass of wine (she hasn't slept without some….help….for a while now) and then sleep.

Thunk.

Alex blinks in surprise. At first the sound doesn't register, and her sleep-deprived brain fumbles to come up with a source. Keys. She threw her keys on the table. But there was no metallic clinking noise. The hell?

She turns to look, and her gaze falls upon the keys, which are sitting on top of an envelope. It doesn't look like mail; there's no stamp or return address, and the only person who could have brought it in is Astra, who she's almost positive doesn't even know what a mailbox is. Alex moves closer and picks up the envelope, and her heart crawls into her throat as she sees her name written on it.

That's Kara's writing.

Alex's heartbeat thuds in her ears, and she almost rips the envelope in half in her haste to get it open. Tears are already burning her eyes.

Alex,

I don't know what to say to you. I don't know how to express how sorry I am. What I said….I'd be lying if I said it wasn't true. We both know that. But I never meant to hurt you. I never, ever wanted that. You have always been there for me, always been my strength even when I didn't deserve you. And I threw it all back in your face. I can't ever forgive myself for that.

By the time you get this, I'll be far, far away. I want to make sure I can't ever hurt anyone ever again. Least of all you. When I became Supergirl, I didn't do it just for National City. I did it for you. You've spent your whole life protecting me; I wanted to protect you, Alex. My sister. My friend. My everything. But I failed. I failed so completely that I don't think it can be fixed.

I love you, Alex. I love you so, so much. I can never thank you for everything you've done, everything you've been, for me. My life on Earth would have been so horrible without you—actually, I think I might have turned into a monster without you. I might have joined Aunt Astra and Non. You taught me to be human. You showed me how not to be afraid. You promised me I would never be alone. And you never stopped believing, even though I don't deserve it anymore. From the bottom of my heart, Alex, thank you. Thank you, thank you, thank you.

I told you that you had no life without me. Well, that doesn't have to be true anymore. Go. Find yourself, Alex. Find who you are, not who I needed you to be. I think you can do it. Hell, I know you can. You might even be surprised at what you find. I wish I could be there to see it, but I know as clearly as I've ever known anything that this is for the best. Just promise me you'll be happy.

You will always be in my heart. I love you, Alex.

—Kara

The world stops as Alex's eyes zoom over the page. Her grip gets tighter and tighter, vision blurring until the words swim together. Alex's knees buckle and she sinks to the floor, because this can't be true. It can't be. Kara can't be gone, vanished into some unknown corner of the world without her.

If J'onn were still in charge, Alex could hightail it back to the DEO; could use every technology known to man to find her sister and bring her home. But she can't. J'onn is as good as dead; they both know it, even if the words never passed between them.

She can't have lost her little sister.

But she has. And now…. Kara is never coming back.

Alex is utterly alone.

Something builds inside of her, something deep and ugly and primal. It tears at her throat with razor claws, punches out her chest and makes her bleed. Alex crumples the letter in her hands and screams, shattered, stripped of everything that's ever mattered to her, every reason she ever had for fighting. She screams and screams, her heart somehow still beating even though surely she must be dead, surely this must be hell, because Alex can't even fathom a world without Kara.

Someone's arms wrap around her, pull her close. She smells earth and wind and leather, knows in some tiny, still sane part of her mind that this person is important, but it doesn't matter. Nothing matters anymore. Alex lets out a horrible cry, struggling in vain against the powerful grip, needing not comfort but to bleed the world and watch it burn, because her world has crumbled into less than dust. "LET ME GO!" she screams, claws and writhes, fists and elbows flying. There is no technique at all, none of the skills she's used every day for what feels like her entire life. Only rage is left; rage and a deep, deep, unspeakable grief. Everything that Alex was is dead, dead as Krypton. Now….she's less than nothing, more animal than human. "LET ME GO!"

"ALEX!"

Time stops. The vortex of rage and grief and pain simply melts away, as if it had never been there in the first place. Alex turns wild eyes to the one who spoke, her heart fit to burst from her chest. It can't be. It can't be. Her family is gone…..she's gone, forever…

But it is. Her baby sister is standing in front of her, eyes wide in horror and remorse, tears pouring down her cheeks. Alex goes utterly still, a tiny, tiny whimper slipping from her lips. Her heartbeat crashes in her ears, drowns out everything else. The arms around her loosen, and she all but leaps, catching the blonde in a crushing embrace and burying her face into a blessedly familiar shoulder.

"Kara," Alex sobs, rough and ragged from screaming. "Kara, Kara, Kara….." She trembles, utterly overcome, reduced to nothing but blessed relief. "Kara…."

It's too much to bear. Everything comes crashing down on her with the force of a runaway semi, and Alex collapses into unconsciousness.