Lena has a secret.
Lena has a secret that is directly related to Kara's secret, that Kara thinks is still a secret, but Lena secretly knows Kara's secret.
Lena's secret is that she pretends to be oblivious to Kara's secret identity and actively helps her hide the fact from herself because Kara would very easily give herself away without a little help.
Some people might believe that it's counter-intuitive to help Kara keep a non-secret from her, but she has a reason; they have been dating for a few months now and she needs Kara to come clean about being Supergirl for their relationship to work out in the long run, Kara needs to show that she trusts her, and she can't let Kara take the easy way out on this one.
She is going to come clean right along with Kara when Kara eventually tells her the truth, but she has to wait this one out, and also help her girlfriend out with keeping her own damn secret because she's so bad at it.
Just a few days ago, Kara walked in wearing her super suit and so Lena had to pretend not to notice and instead asked her to go grab her lipstick for her from by the mirror in the bathroom, so she had the chance to notice and do a speed change before coming back in more appropriate attire for lunch.
How Kara thinks that she is sneaky, Lena will never understand.
Now Lena is pottering around her penthouse, enjoying a rare day off to herself but wishing that she had the company of her favourite person.
Since it is a weekend and there's nothing on the news about anything to do with Supergirl, she decides to send Kara a text asking if she's got time to come over, maybe watch a bit of TV or maybe go check the mattress springs are in working order.
In typical Kara fashion she gets a response right away, the whole thing completely littered with emoji after emoji, mostly hearts. Lena doesn't totally get what a lot of them mean but she does get the message that Kara is on her way and will be here soon.
She decides to pour them a drink each, a couple of sodas since it's still early and Kara gets worried if she does any day drinking, even if it's completely innocent.
Her plan is to wait on the couch for Kara to arrive, maybe use the time to pick something good to put on the TV and ignore in favour of reacquainting herself with her immensely hot girlfriend.
Lena definitely isn't expecting the familiar sound of feet thudding onto her balcony as a certain caped superhero lands. She can help Kara out with her lies to some extent, but this is too much for even her genius brain to plan around.
She swivels her head slowly, praying that it's in her head and Kara didn't just land on the balcony in full superhero regalia, and…yep. Yes, she's just done exactly that.
Kara stands there, beaming smile plastered across her face and a lovely bouquet of flowers in hand, waving at her jovially with her free hand, completely unaware of her mistake. A frown slowly replaces the smile when she sees Lena's horrified expression, crinkle taking its spot on her forehead.
It's only as she's dragging the balcony door open that she comes to the realization of what she's done, the mistake that she's made.
Neither of them speak, both unsure of whether or not they should directly address it, or maybe they're just afraid to.
Silently, Kara slips through the balcony door and closes it behind her, her shoulders slumped in defeat. Lena's just happy that she hasn't flown away, it wouldn't be the first time Kara has panicked and made a run for it or rather, made a fly for it.
"Hi." Kara mumbles.
"Hello."
They keep staring, waiting for the other to speak first, praying that they don't have to be the one to break, but eventually someone has to, and that person has to be Kara.
"I'm sorry, I really was going to tell you." Kara drops the flowers onto the nearest surface, a little side table, and moves around to perch on the edge of the couch next to Lena.
"When?" Lena questions. She wanted Kara to tell her, not fuck up and give herself away. There's no trust in this kind of fuck up.
Kara pauses, looking down at her feet. The gravity of the situation is all too clear, and she has to tell Lena everything, there's no way to sugar coat any of it now and that means that she can only tell the complete truth and hope that Lena can forgive her. "I've been trying to summon the courage to tell you for a couple of months but every time I planned to do it, I would back out at the last second like a coward."
Lena drops her head to her own fidgeting hands, so now neither of them are looking at the other, completely lost at how to make this conversation productive and not say anything based on pure emotion rather than having an honest open discussion.
Eventually Lena sees that Kara is waiting for her to speak, to guide the conversation and she also knows Kara enough to know that it isn't because she doesn't have anything to say, it's because she is giving Lena the chance to process and guide the conversation within her comfort zone.
"I already knew, Kara. I was waiting for you to tell me…I was waiting for you to trust me." Lena whimpers the last part out, tears now streaming freely down her cheeks but lacking the energy to wipe them away, knowing that even if she did, they'd just get replaced right way anyhow.
Kara's breathing picks up audibly, worrying Lena slightly but Kara talks before she can ask if she's alright. Kara may have hurt her but she's still her girlfriend for better or for worse, and she still loves her.
"I'm not going to ask how you knew because I know that you're a genius who figures everything out and I've been getting sloppy at hiding it, I guess that was also my way of testing the waters a bit, trying to figure out how you'd react, but that wasn't fair of me, so I'm sorry for that too."
"Kara –"
"Wait, let me finish, please." Kara cuts her off gently. "I do trust you though, with every fibre of my being. You are my emergency contact in everything, even with the DEO. You are named on my life insurance. You are my power of attorney. I love you and I would have never let our relationship get this far if I didn't. I really have been trying to tell you, I just got scared, it's always been drilled into me to never tell anyone, so it was eating away at me when I shouldn't have let it."
Lena is taken aback. Power of attorney? Life insurance? Holy cow. "You'd really let me make medical decisions for you if you couldn't?"
"You're the only person that I trust to make decisions that would actually be in my best interest, no offence to Alex, and if we were in a situation where I couldn't make a decision like that then I would be in a bad way, and you would be stressed and in desperate need of some kind of control so it would be good for you."
Lena hesitantly places her hand over Kara's. "You've really thought about this."
"I have, because you're the person I trust most, and love most." Kara turns her hand over to grip at Lena's, intertwining their fingers.
Lena nods once, "Alright then. I guess I just have to trust you on that, but that's not too hard because I love you too."