LW: It's probably because I've become kind of addicted to Grimm right now, but tada Supergirl/Grimm crossover

Monroe: Hey guys, Supergirl is CW's, Grimm is … um Lonly doesn't do research well (which means the Undertale crossover may take a while) so all we know is it's not him

Kara: Enjoy!

I see what can't be seen

Ever since she got to earth Kara found she could see things. These beings looked human for the most part but at times their faces rippled and transformed into frightening monstrosities. What made things stranger was not only did nobody else notice these changes, but the few that saw her staring turned deathly pale and shifted back, some muttering something grim before running off. A part of Kara wanted desperately to chase after them to get answers but she knew better than to cause a scene.

This phenomenon persisted even when she got a job in CatCo, stressed workers letting their faces slip, as well as just under half the people who had direct meetings with Cat. Of course at this point Kara made sure nobody knew she could see them, keeping her head down for meetings and very slightly avoiding eye contact with her colleagues. Sure it gave her a reputation as Cat's meek assistant (One grumpy looking man resembling a goat called her a mauzhertz, whatever that was) but it was better than scaring off or worse being attacked by one of these people. She came pretty close to this when Siobhan turned into some kind of bat creature just before her shriek sent her out the window but Kara was sure there hadn't been enough time for her to realise whatever it was these people saw in her.

Her questions were finally answered by a surprising source, in unexpected circumstances. The explosion on the Venture meant both her and Kal… Clark were making their way to the National City division of LexCorp. Walking right past the assistant who squeaked at Clark's scowl they barged in on the company's new/current CEO: Lena Luthor. It was actually while Clark was attempting to subtly search the office it happened.

'I know why you're having this little witch hunt, it's because I'm a Luthor' she hissed and her face morphed before her eyes; midnight black hair turning slate grey, those emerald eyes faded to hollow sockets, her skin turning leathery and partially decayed, while her near lipless mouth held pointed teeth. She sneered at Clark's back, but when she turned to Kara her face jolted back and she turned paler than before.

If Clark noticed any of this he didn't say anything and if he didn't see Kara wasn't going to bring it up, having been told enough times by him to 'be more observant' and 'watch your surroundings' plus he already had a hate-on for all things Luthor she didn't need to give him anything else.

The next time Kara actually got to talk to Lena was about a week later when Snapper sent her over for an interview. She entered the office and Lena looked up before sighing

'Give me a minute to change my will before you kill me. Okay, Ren gets the company, and our AI research goes to Ryder and Afton'

Kara blinked 'Wait, why are you dying?'

'Because you're a Grimm and I'm a Hexenbiest. Is this how you do it these days, making me tell you why I must die so you don't feel guilty about it after?'

'No. I'm not her to hurt you. I'm a reporter now, I was sent over to interview you, plus I kind of hoped I could talk to you about … well this' she waves her hand around her face and Lena nods in understanding before chuckling

'My, my, a baby Grimm in National City, this is a surprise. So I presume you've been seeing wesen woge but this is your first actual discussion about what you're seeing?'

'Wesen? Woge? What?' Kara asked in confusion

'Wow you are fresh off the boat aren't you? Did your parents teach you nothing?'

They died when I was 13, I was adopted by humans and it was a little after that I started to see... vesen' Kara explained, it actually felt both strange and freeing to differentiate herself from the Danvers after so long pretending to be a human, admitting she wasn't one to Lena even if she doesn't realise what she means specifically.

Later that evening Kara left with her questions answered both the ones for Snapper and her own personal ones. Meanwhile Lena had an important conversation to have

'Why didn't you tell me there was a Grimm in National City?'

'What! What do you mean a Grimm?' the woman on the other end yelled 'How can there be a Grimm in MY city?'

'I mean a Grimm as in someone who can see us with Hellfire in their eyes, specifically a CatCo reporter by the name of Kara Danvers'

'Ke… ha, ha, ha, ha' the laughter from the other end confused the young Luthor

'Um, what's so funny?'

'Kara's not a Grimm, she's Supergirl. It turns out Kryptonians can see us too'

Lena gaped 'What! How the fuck do you know this?'

'Kara blew out her powers earlier in the year, I managed to get some blood and make a charm so if she came within 20 ft of me I'd know. It confirmed my suspicions as glasses and a hairdo a disguise is not'

'So what do we do?'

'She'll most likely want to know more so show her the database, I'd give her my father's books but I'd rather not expose myself just yet'

'Of course sister'

'Sister? Something must really be wrong with you little Luthor to talk to me like that'

'Oh fuck off Queenie!'

The smirk was practically audible 'That's better. Bye little sis'

She had been right, Kara did show up the next day with more questions and a sunny smile, skipping past Lena's assistant despite the girls best efforts, a feat that privately amused Lena even thought she knew it was well within Supergirl's capabilities especially given Jess wasn't a wesen known for speed or strength.

'Hello Kara, what can I do for National City's best?' she greeted with a smile, surprised by how natural it felt

'I was hoping we could talk more about wesen, I've been seeing them my whole life but I never really had a chance to think about them in any sort of capacity, how many kinds are there? Are any friendly? Are any bad? With aliens like Superman and Supergirl flying around are there Wesen with abilities that could be seen as alien, and would they try to be heroes or villains?'

'Well that last one I can answer, Lex was like me so wesen can be just as capable to be a hero or a villain as any human or alien. But the others… well I think I should show you something the wesen community has created recently. You familiar with the so called alien internet?'

'Of course, the extranet. My sister works with alien policing' Kara explains, hoping this never gets back to Alex or she'd be in the shit for months.

'Well let me show you a little corner of the deep web we hollowed out for ourselves' Lena mutters, her hand brushing against a scar behind her ear as she types in an address.

Scanning…Scanning… Acquired

Hex LL has entered Woge

'Woge? Little on the nose isn't it?' Kara jokes before she sees what has been unlocked: a full community in front of her, miles of text flowing past the screen

'Wait, what's Hex LL mean?' she asks after a few minutes

'It's what I am, HEXenbiest, followed by my initials. Its how all wesen are logged in, I'm just glad there weren't many Hexenbiests with my initials, Hex LeLu sounds stupid'

'But isn't your mother LL too?'

'True but she'd be LS, her maiden name is Lillian Shade. I actually have 2 cousins through her, or at least Lex does: One messed with a Grimm and lost her powers, then there's Zara who is actually how I imagine you if you were an alien Hexenbiest rather than an alien Grimm. She's one of the best assistants I've heard of and you won't hear a word a bad word from her boss… even before she started seducing her boss' Lena laughed at Kara's shocked expression

'So how exactly do you stop the humans… or I suppose you're technically human yourself so whatever you call normal … anyway how do you keep them out of this little wesen hotspot?' Kara asked curiously

Lena grinned proudly 'They're called Kehrseite and Woge has some of the best security and countermeasures this world has to offer, I should know I helped design them'

'What!'

'Well technically Lex-Corp builds them but I designed and built the first prototype for the implants' she answers, pushing her ear forward to show Kara the scar directly behind it 'The device is detected by the interface and if it gives the all clear you can enter. It's actually why there's a dial-up in the time of instant internet. There's also a secondary function as a translator, as a Hexenbiest it's default is German but I have it set to English at the moment, sometimes Irish when I'm feeling nostalgic. If you could give us a sample of the language I'm sure we could have the implant set to translate text to Kryptonian if you like, if nothing else it'd be good for privacy'

Kara froze 'I-I-I'm not…'

'Kara really, glasses aren't a disguise and this lie would collapse the first time Supergirl saw me woge. Now I'd offer you the surgery when I'm next free but…'

'Given who I am you'd need Kryptonite and given your last name my sister would sooner shoot you in the face then let you get anywhere near me with that'

'Exactly. So maybe next time you blow your powers you come in and we'll do it quickly. Now lets just let that settle and I can show you the real reason I showed you this. The wesen archives, also jokingly referred to as the Grimmopaedia due to the fact most of the initial information was taken from the family ledgers of several Grimm, as well as several very detailed drawings' she said letting the program jump to a random wesen which in this case happened to be a Blutbad.

'Wow this is incredible. But why is it here?'

'Many Grimms realised there were problems with the mostly trial and error method of dealing with criminal wesen, even the ones with family journals. It was that concept that lead to the Grimmopaedia, one single database of all things wesen. The wesen community and even the council are okay with this because they know not all their people are good, Coyotls for examples are almost all inbreeding brutish thugs, while the majority of Hundjagers are literal attack dogs for the Royals'

Kara nods 'I understand, even though I though I want to show the world me and…'

'Clark?' Lena offered with a smirk

'…Kal are good, I understand the need for things such as kryptonite weaponry, Non and the other kryptonians from Fort Rozz show that fairly well

Lena nodded 'While I didn't plan to use a personal example I'm glad you didn't need one. Still most of it is information about the wesen species, common traits and noticeable quirks about the species as well as their usual strengths and weaknesses. Though for you Kara, once you get your implant, you'll have access to this' she brings her cursor to an icon that resembled a stylized 'G' when the arrow turned into a red X 'The information that shows these were Grimm archives: Historical accounts of confrontations between these wesen and Grimms, as well as how to kill them' she noticed Kara pale at the very idea and sighed, Superman really did teach her everything 'I'm not saying you should kill but knowing how to take them out if you ever needed to is important, it could actually save lives'

'Sigh I guess you're right Lena. Now budge up and let me see this world'

After that they fell into a comfortable pattern of lunch meetings and conversations both wesen related and just friendly banter and bonding. Things were pretty quiet over all up until the day Maggie and another officer arrived looking for Lena to arrest her.

'You're doing this because of my last name, it doesn't matter how flimsy the evidence it's a Luthor so she must be guilty' Lena growled as she woged, Maggie and her partner following suit.

Despite herself Kara was a little amused her suspicions from Maggie's eyes were true: her sister was dating a Blutbad. The other guy was some kind of otter looking creature; she was going to have to look that one up later.

'Grimm!' the man yelled as they all shifted back

'Back away from Lena' Kara ordered, pushing just enough of her power for her eyes to glow

'You sure about this Little Danvers? You ring this bell it can't be unrung' Maggie whispers

'Most of you guys think I'm a Grimm anyway, might as well accept it' Kara answers with a shrug

Maggie growled angrily before sighing 'Fine. Just make sure she doesn't leave town till this is over' she says before both leave and Lena releases the breath she was holding

'Kara you didn't need to do that'

'Yes I did, I wasn't just going to let them take you in for something you didn't do. I'm not someone like Lois Lane, my name doesn't mean anything as a reporter and I can't just out myself as Supergirl to some cop so the fact all wesen think I'm a Grimm gives me something I can use to help you

'Oh Kara'

BEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEP

Lena groaned as she answered her phone 'Yes?'

'Why did I just hear 2 officers were in your office? Al didn't get out did he?' and angry and familiar voice yelled, Kara's eyebrows raise in surprise

The Hexenbiest sighed 'I don't know whether to fire that girl or give her a raise'

'Give her a raise, one of us should pay our assistants what they're worth'

'It's all good, Kara was here and she even outed herself as a Grimm to help me'

'But she's not a Grimm'

'Yeah, but they don't know that. Plus she's practically one so that's all that matters'

She chuckled 'You're right, tell Kara I said hi. Bye little sis'

'Bye Queenie' Lena replies before hanging up 'Sorry about that, overprotective siblings. Used to be Alexander but this one's been doing his job since… you know' Kara nodded, she knew what Lena was talking about, as well as why she didn't want to finish the sentence

'Don't I know it, Alex would be the same if I ever was to get nearly arrested, especially as her girlfriend just showed up to bring you in' Lena winced

Sorry about that Kara, I hope it doesn't cause any problems between you later'

'Don't worry Le, it'll be just fine. See you later then' Kara smiles her usually megawatt grin which Lena returns

'Okay darling, just tell Jess she did good on the way by K?'

'Sure'

Leaving the office Kara stopped at Jess' desk 'Hey Jess'

'Hello Ms D… Kara' the girl corrected herself at Kara's playful glare

'Anyway I was just about to leave and decided to pass on Lena's thanks for the swift call to her sister'

'Oh it was nothing, reflex really. I've been paranoid someone was going to bring her in because of her name. This was much worse than I thought …' as Jess rambled, her features pinched and small, cute mouse ears peaked out of her hair, causing Kara to coo unconsciously. Jess looked up and actually squeaked 'You're a Grimm! Please don't kill me, or Lena. She's trying so hard to be better do things right, plus I have a family to feed please spare us'

Kara panicked as she tried to calm the mousy wesen 'Hey, hey, hey, Jess calm down. I'm not here to hurt you guys. I'm not even really a Grimm, I'm… Lena! Should I tell her what I am?'

'It's not my decision to make, it's your secret to keep or share' Lena called from her office

'Okay. Jess I'm not a Grimm, I'm Supergirl. Kryptonians can see wesen too'

This didn't help much 'Supergirl! Don't hurt Lena, she's nothing like the rest of her family, she's trying her hardest to be better and make things right plus she does things for the Wesen community. I mean I came to her with my wife; the most beautiful Fuchsbau I've ever met with the sexy librarian look: and now we have this little fluff ball of a son, his name is Alex by the way' Kara raises an eyebrow 'I'm over sharing again aren't I?'

Kara's laughter confirms it for her 'A little yes but it's cute. Lena's no just your boss is she?'

'No, she's my friend and Alex's godmother. People ask me how I can be loyal to a Luthor, it's because she isn't just a Luthor she's Lena and she's practically family'

Meanwhile Maggie and her partner had to report their failure

'You mean to tell me you practically had that Luthor Hexenbitch cuffed and you let her go?' the chief growled, the Jägerbar woging for just a moment in his anger.

'It's not that simple, we did try to arrest her…' Maggie started but her partner interrupted

'…But the Grimm practically threw us out of the office. We have enough trouble on the human side of things with Supergirl. The alien has saved her life so often I'm surprised she didn't appear just to kicked us through the wall or out the window' he grumbled, despite herself Maggie found amusement at how close that statement was to being true.

'Wait we have a Grimm in National City?'

Maggie sighed before answering 'Yes. Kara Danvers, CatCo reporter. I believe she's done quite a few articles on Luthor as well as alien issues. She's also my girlfriend's sister... Adopted sister' Maggie stressed the adopted part, not wanting any wesen related shit going in Alex's direction, especially given all the alien shit she has to deal with in the DEO and as Supergirl's big sister. She already knew once her mom heard she was dating someone she'd be looking for a Hexenbiest for the ritual, she really didn't need her threatening Alex and outing them as wesen over assumptions and false information.

'You think the Grimm's sister could talk her out of this stupid blockage of hers?' the chief asked, to which Maggie just shrugged

'Maybe, Alex and Kara are both pretty stubborn but it's possible'

'Good, get to it'

Later

The moment Kara entered the DEO she was dragged into a lab by an angry Alex Danvers 'Seriously Kara what were you thinking defending a Luthor like that?'

'She's not just a Luthor she's my friend and she's innocent, they were only taking her in because like you they see her as a Luthor'

'Kara…'

'Before you say I don't know anything or my friendship is blinding me like Clark & Lex, I saw the video and it's obviously fake: With a chunk of kryptonite that size I'd know if Lena had even just been around it, and if she'd done what she did in the video just being near Lena would be nauseating for me. She's being framed and because she's 'just a Luthor' nobody but me seems to give a damn!'

'Kara…' Alex was once more interrupted

'Just have Winn check the footage, if he actually tries and can't find anything I'll let it drop but if he finds anything we send the information straight to the police'

'You think he'd actually do that?' Alex asks sceptically

'If you tell him you're concerned a Luthor is affecting my judgement or thoughts he may be inclined or convinced to 'not find anything' if you catch my drift' Kara retorted, Alex sighed knowing she was right

'I'm just trying to protect my sister'

'And I just want to help my friend'

Winn was about half way through scanning the video when alarms blared

'Lena' Kara yelled, turning to leave

'I don't know how you do that but you're right' Alex sighed before continuing 'Disturbances at L-Corp, looks like Metallo and Henshaw have arrived to collect Ms Luthor

'Well if she was part of it there are easier ways to do this' Kara argued 'Subtler too'

'Not if she wants to hide her involvement'

Kara sighed 'We'll talk about this later' she grumbles as she flies off before Alex can say anything else

'Let her go!' Supergirl yells as she flies into Lena's office just after Metallo and Henshaw had grabbed her.

'I think not' Metallo drawled as he unbuttoned his shirt, exposing his kryptonite heart. Kara feeling the familiar pained buzz in her brain

Supergirl charged her heat vision and as her eyes met the cyborg she faltered in surprise: Hank's human eye had turned pitch black and Kara saw herself in full solar flare reflected in the void. That momentary hesitation was all Metallo needed to fire a kryptonite beam, tossing Supergirl through the glass window of Lena's office

Kara pushed herself up on her hands and knees, glaring as they started pulling Lena out of her office 'What are you?' she hissed, surprisingly getting something that was a mix of a sneer and a smile as he walked over to her

'Alien scum, you're a mockery of a human and a mockery of a Grimm, an abomination like you will soon be purged by Cadmus' his response was followed by a blow that broke through the balcony and caused her to leave a small crater in the ground below.

That evening

The unstable kryptonite signal lead her to a hidden base in the mountains, once she entered Kara decided to make her prescience known by blowing up the security panel on what looked to be an enormous box of death. Landing with a thump she smiled to Lena who was the first to see her.

'What have you done?' Lillian shrieked, her woged features contorting hideously

'Supergirl, you shouldn't have come' Lena called, fear and worry on her face

'I'm Kryptonian Lena, I can't just let those important to me get hurt' Kara retorts with a grin and a wink

'Well I guess we'll just have to get rid of you' Lillian tilted her head and Metallo shot her with another beam, Kara yells as her insides feel they're on fire, dropping to her hands and knees. The pain faded and dark chuckles filled her ears, looking up she saw Lillian standing over her with a smug grin.

'Such a powerful being, brought down so easily by your superiors. You will die alien, and we will ensure all those like you will be removed from our planet forever. There is nothing a creature like you can do to stop me' the Hexenbiest's grin looked sickening to Kara, but it put a thought in her head.

Kara chewed her lip, super strength meeting invulnerability, ironically assisted by the large amount of kryptonite in the vicinity

'I've been denying parts of myself for so long, claiming things I hadn't believed. But now I see it, I am a Grimm!' Kara spat angrily, getting Lillian in the face

The woman flinched and moved to wipe it off when she grimaced and fell to her knees in pain, ripples of woge flickering across her face. Seeing him distracted (being one of the few who knew what was happening) Kara shot forward and slammed her fist straight into Henshaw's face, putting some distance between him and Lena before picking up the woman in her arms and running. They had just reached the doorway when Lillian screamed and they turned to see the Hexenbiest spirit leave her.

'What have you done to me?' Lillian hissed, much weaker than Kara or Lena had ever heard her.

'I took your powers away, you're a human now'

'You really are a Grimm after all' she sneered as Henshaw helped her up, Kara escaping before any of them could try to retaliate

A little while later

With some prompting a reluctant Supergirl dropped Lena off at her office, the woman groaning tiredly before dropping onto her sofa.

'Are you sure you don't want me to drop you home?' Kara asked once more

'No Kara, I'm fine' Lena answered without opening her eyes 'You really shouldn't have come for me' she hears the fabric shift as Kara sits down beside her

'What are you talking about; of course I would come save you'

'They had kryptonite and were trying to get me to open one of Lex's vaults which contained even worse concoctions' she turns and looks the kryptonian right in the eye 'This city can go on without me, it can't without you'

'The city might, but I can't' Kara mutters, then blushed bright red when she sees Lena's confused expression, she'd heard her.

She quickly drains the glass on the table, swirls the water around before spitting like a fountain in what would be quite an impressive arc out over Lena's balcony

'What the hell was that for?'

'I didn't want to hurt you' Kara answers meekly

'Oh Kara how could you possibly hurt me?'

Rather than answer Kara surges forward and captures her lips in a quick kiss, little more than a peck but that moment felt like flying for the 1st time: light, free and brimming with joy.

'You're my best friend, we've spent so much time together and getting to know each other, I've fallen for you. I know I'm a Super and you're a Luthor, plus I'm a Grimm and you're a Hexenbiest, but I still needed to let my feelings out. Now you probably don't feel the same and that's fine I still want us to be friends just try let me down…'

Kara didn't get to continue her rambling as Lena pulls her by her collar (only shock enabling it to be possible) and properly slamming their lips together in a stronger, more passionate kiss, the kryptonian noticing despite the danger, sharp teeth uselessly nibbling on her lower lip.

'Oh Kara' Lena whispers breathlessly 'How could I not fall for you?' she gives another quick kiss before being pulled onto Kara's lap and cuddled 'My Grimm, my Supergirl, my Zweites Herz'

Later - DEO

'Um Kara, why aren't you under the Sun lamps?' Alex asked with a mix of concern and curiosity

'Oh, I'm just waiting for Lena to finish filling out the Supergirl NDA'

'You told her!'

'She already knew, but yeah I did outright say it once we became official but that's because I didn't want any secrets between us'

'Official… Oh my god Kara you finally asked her out?' Alex cheered

'Yes. Wait, what do you mean finally?'

Alex laughed 'You may have super vision but you can't see what's right in fucking front of you. You've had feelings for Lena practically since you first met. I was worried she'd break your heart, until Maggie and her fully functional gaydar showed up and told me there was a chance. I'm glad you got this Kara you deserve happiness. Though you're telling mom you're dating a Luthor'

'Can't be any worse than telling her I'm dating a Hexenbiest' Kara thinks just as Lena exits the office.

THE END (Or is it? Yeah it could be)

LW: Well that was fun, technically this is it but I may have a little fun with this universe and add bonus chapters that expand everything. Also not really a spoiler, more a fun fact but Astra's still alive in this universe, and a few more important Supergirl characters are wesen