Heartstrings Twisted

Summary:

A minor tragedy brings a new face to the Avenger's Tower. A new face who identifies herself as Tony's sister, though not in name.

Author's Note:

This story is written for fun. This will also be an eventual Bucky/OFC romance, but slow-build. This is a rather typical story line, but I plan on making it different for a reason. The biggest reason: Cas will NOT become an Avenger at any point. She will be familiar with the team as time progresses, but definitely not an Avenger. I'm going off of canon-movie that insinuates Tony is about twenty-seven when the first Iron Man movie takes place, and as the series of movies aren't finished yet, this takes place somewhat in the future (about three years), after all the chaos is over. So, Tony is about thirty-two, which places Cas at twenty-five. I won't be going into any details of the movies, but instead just playing with the characters.

Chapter One
Flare

Her fingers tremble. It isn't noticeable, the fine tremors nestled beneath the heavy, grey wool of the shock blanket the EMT's had thrown over her shoulders in haste. Light hazel-green eyes peer up at the building that once housed her loft apartment and she can feel the tightness in her chest grow with each passing moment. There's a pounding in her ears, the faint twitch of her pulse pumping just beneath her pierced earlobe. The tension isn't new, but definitely not welcome. She ponders over the loss, all of her things, everything important trapped within the burning inferno the firefighters were struggling to contain and put out.

Stupid fucking college douchebags.

"Cassie!"

At the familiar, slightly frantic voice, the dark-haired woman blinks and finds herself staring into bold, bright blue eyes surrounded by white-blonde hair. Gorgeous and tall with curves in all the right places, Tatiana Goldsmith is the epitome of everything she could never be. Blinking, the dark-haired, dazed young woman realizes her dear friend has been calling her name, repeatedly if the worried expression is anything to go by.

"Tia," she murmurs, feeling a warm, sun-kissed hand gently clasp her cold, pale and trembling fingers, "Tia...they're gone. All of 'em."

"I know, Honey, but you're still here and we can fix everything else," Tatiana says, her other hand moving to rub up along the side of the blanket, the friction helping to bring more warmth. "C'mon, let's get you out of here. Did the EMT's recommend a hospital visit for you?"

Hazel eyes watch as a long black bag is wheeled out to one of the ambulances, the stench of charred flesh causing her stomach to churn, "No. No hopsital. I want to go home."

The young woman is so deeply thankful that she doesn't have to elaborate more than that. Tatiana nods her head and helps her to her feet; guiding her toward the beautiful sporty car. The moment her head rests against the back of the seat, she is poked in the shoulder, her eyes popping open to find a sun-kissed palm holding two pills. Sighing, Cassie pops both of them without prompt and swallows a mouthful of water from the offered bottle.

"Thanks, Tia." Cassie sighs, her forehead coming to rest against the cold window.

Rock music plays softly, the silence between them comfortable, despite the heaviness the tragedy brought. Cassie lets out another sigh as the scenary passes her by and her eyes slide shut; training her focus on the music.

It's early evening at the Avenger's Tower, various team members all seated at the large table. Multiple conversations flowed at once, mixing together in a vortex of friendly bickering, scientific babble and pop culture references. It had taken a lot, many years and a decent amount of in-fighting for the team to have grown comfortable enough that even the harsher jabs of humor earned a response of sharp laughter and even sharper wit. It wasn't often that the team was able to come together, everyone busy with their everyday lives; but once every two weeks the team would settle in for a dinner and catch up.

This evening, Bruce and Tony conversed over topics that no one else could really understand. Bucky and Natasha bantered over horror stories, their words shifting from English to Russia with an ease that leaves all those around them confused. Thor is regailing Clint and Pepper of his most recent trip to Asgard, of Lady Sif and the Warriors Three. Sam and Rhodes were throwing out new pop culture information Steve is still trying to catch up on.

The dinner is a pleasant one.

"Sorry to interrupt your dinner, Boss," the feminine AI, Friday, calls out suddenly, "but Miss Cas is currently taking the private elevator up to your current position."

The interruption causes Tony, Rhodes and Pepper to all jolt out of their chairs, Tony's eyes wide with concern, "What kind of state is she in?"

"Elevated heart rate. Minor neurotic twitches. Hitched breathing. She doesn't seem to be visibly responding to anything. I'd go so far as to say she is in a minor state of shock, Boss."

Tony nods and turns his gaze to his fiance, "Pep, can you put a kettle on the stove?"

Pepper leaves the table after pressing a soft kiss to his cheek. The team watches as Rhodes, who already made it around the table, places a hand on his best friend's shoulder. Rhodes whispers something that is too low to hear and Tony nods curtly before the dark-skinned man slips out of the kitchen. Various members of the team share looks of concern when the resident genius billionaire begins pacing back and forth, his hand constant combing through his hair and tugging at it with a nervous air. Steve eyes his friend with worry.

"Tony-"

A small chime sounds as the elevator doors open. All eyes watch as a small, petite woman steps off, her gait stilted and forced. Her simple loungewear clothing ruffled and multiple rips decorate the fabric. Dark, unkempt curls frame a pale face, hazel eyes blank and not even acknowledging the rest of the team as her gaze focuses on Tony. She doesn't slow, nor does she speed up. She doesn't even stop her approach until she walks full-bodied into Tony, his arms not even hesitate to embrace the silent girl. Tony tightens his grip around the girl, inhaling deeply. His shoulders tense before he gently pulls out of the hug, his hands resting on her upper arms.

"You smell like smoke."

"My building caught on fire," the girl replies, her voice toneless.

"While you were inside?" The team aren't sure how this person has managed to make Tony Stark sound frantic.

She nods curtly, holding up her hand to show the minor burn marking her palm, small cuts and knicks along her fingers, "I'm fine."

Tony's finger trails over the burn mark, "Fire escape?" She nods, "How did you get here?"

"Tia gave me a ride."

Tony makes a small humming sound, "What happened?"

"A bunch of dumb ass college kids decided to party like a boss," her voice tinges with a sharp, angry sarcastic edge, "and when their curtain caught on fire, those drunk assholes ignored the fire estingquisher and used whatever booze they had to try and put out the fire."

Tony give a low sounding groan at the utter stupidity, "How bad is the damage?"

"Irreversable. Absolutely nothing is salvageable," her tone grows more firm as a desperate anger flickers through her eyes, "My phone. My tablet. My cat. My fucking bed." She mindlessly jabs Tony in the chest, "And the worst part of it all, is all of my fucking clothes; every last scrap, all of it, gone. My clothes, Tony."

A harsh disbelieving scoff sounds from the dinner table, and Bucky's voice cuts through the pair, "You're upset over clothes? "

Tony visible winces as the girl's spine straightens and her light hazel-green eyes instantly pins on the ex-assassin, "Oh, I'm sorry," Bucky blinks at the genuinely apologetic tone, despite the sharpness of her gaze, "Do I know you?"

"Not that I'm aware of," Bucky quips.

She nods slowly, humming, "Right, and do you know me?"

Bucky lets out a bark of a laugh, "Dollface, I'm pretty sure not a single person sitting at this table knows who you are."

The smarmy tone in his voice causes Steve to shoot his best friend a glare, but the woman's head tilts, her eyes assessing Bucky and her expression softens, "Aww...now that's just adorable" Even though her expression was coy, there was a faint, underlying tone of dry, cynical wit beneath her voice, "Tony, you never told me your newfound friends were all so snarky and judgemental. It really makes a person feel all warm and fuzzy inside."

A few members of the team wince at the sarcasm, but Bucky only sits more upright in an attempt to respond, only for the girl to wave dismissively, "Meh. While I'm sure this conversation is bound to be extremely stimulating, I really don't have the care for it," Bucky's mouth shuts almost immediately at her words, her attention falling on Tony once again, "It's been a very long and trying day and I'm pretty damn sure my threshold is stretched thin enough as it is," Tony startles, his glare pulling away from the dark-haired ex-assassin, the concern obvious. The woman simply pats his cheek with a gentle touch, "All I want to do is crash for the next sixteen hours and wish upon everything that might be holy that this day is just a very bad dream."

"Hello, Cassie."

Every person in the dining room perk up at the sound of Pepper's greeting, the strawberry-blonde CEO approaching the snarky, slightly-rude woman. Those watching are surprised when a genuine, but small smile appears on the dark-haired woman's lips, her eyes lighting up, "Hiya, Pep."

"Here. It's Chamomile, two sugars, and a twist of lemon," Pepper says, handing a mug of tea to the woman.

Those with a well-trained eye notice Cassie's trembling hands take the tea from the red-head, her eyes sliding shut as she inhales its aroma deeply, "Mmm..." She doesn't hesitate to draw her first sip and as her eyes open, the hazel-green depths seem lighter, "Honestly, Pep, you are a saint among insects. If you ever get tired of Tony's bullshit, you let me know. I would bed you myself if I thought you were game."

Tony's hand slaps against his own forehead, even as Clint, Steve and Sam choke on their own tongues. Surprisingly, Pepper flushes a faint, pink hue and giggles at the young woman, "You talk as if you wouldn't be a handful."

Cassie's friendly smile turns into a sultry smirk as her eyes flick down to her own chest, then back to Pepper, "Oh, definitely more than a handful."

"Cas!"

"Tony!" the woman cries out mockingly.

"Will you please stop hitting on Pepper?"

Cassie taps her chin thoughtfully, "Have you sealed the deal yet? Exchanged vows?" Tony groans and shakes his head, causing Cassie to wink in Pepper's direction, "Well, then no. I don't think I will."

Pepper lets out a small, twinkling laugh, even as Tony leans close to the newcomer, eyeing her face. Tony sighs and nudges the hand holding the tea, "Drink up. Your exhausted and your meds are kicking in."

"Mmhmm...where am I staying?"

"My room," Tony replies, his tone leaving no room for arguments, "I was planning on pulling an all-nighter anyway with some last minute diagnostic tests for some new tech the company is putting out. So, you can take me room. Rhodey should be done fixing it up."

"Mmm...well, since you have Pep, can I sleep with Jay?" Cassie flutters her eyelashes, "I promise it's only to cuddle."

Tony lets out a small, honest laugh and embraces the woman once more, kissing the side of her head, "Yes, but keep those crafty hands of yours to yourself. You have your own best friend, no need to steal mine."

"Careful there, brother dearest," Several choked noises and sounds of shock fill the room as Cassie pats Tony's cheek once again, "You're starting to make it sound like a challenge."

"Go to bed, Cas!"

The young woman sighs, nodding her head before pressing a kiss to Tony's cheek before disappearing from the dining room. Tony stares after, even as Pepper shoulders her purse and kisses Tony's cheek, "I'm going to make some calls and clear your schedule for the next two days. Don't forget to check on her in a few hours."

"You truly are a saint, Pep," his gaze softens, "Take my card tomorrow and see about getting Cas some clothes. Friday, I need you to air out one of the guest rooms and modify it to Cas' settings."

"On it, Boss."

Pepper nods and is given a gentle kiss for her help before she slips out of the kitchen.

Utter silence. The sudden tension in the room is sharp and heavy.

"Did she just call you brother dearest?"

Clint's question causes Tony's shoulders to tense, and even as he turns to face the team, his entire stance is defiant, from clenched jaw to squared shoulders and straightened posture.

"What of it?"

Steve pushes up to his feet, "I thought we were past keeping secrets from each other."

The usual Stark-smirk and haughty, know-it-all expression is missing as Tony stares blankly at the blonde super soldier, "I'm pretty sure we agreed that we would no longer keep secrets that directly effect the team. Cas is not, and will never be a member of this team."

"How in the hell is it that the world doesn't know about there being another Stark running around?" Clint blurts out.

Tony drops his gaze briefly, his expression veiled by memories, before he says, "I was five, maybe on the verge of six, years old the first time I was ever kidnapped and used for ransom against my dad. When my mom was pregnant with Cas, she pleaded with my dad to keep it quiet, that she didn't want the new baby placed in danger. My dad was reluctant, until Cas was born," Tony's somber expression shifts with a small smile, "Dad made the doctor and the at-home nurses sign Non-Disclosure Agreements, that they would never speak of Cas' birth. Everyone outside of family and the houseworkers who came across Cas were forced to sign them."

"Your parents hid the fact that they had a second child?" Thor's deep voice is booming, even when it is soft.

Tony nods, "Cas was home schooled, and when she started showing the typical accelerated intelligence that all Stark's possess, her tutor sat with my parents and went over options. So, Cassandra Stark became Cassie DuBois and attended a specialized all-girls boarding school in New England."

"Yeah, well Pepper and Rhodes seem to know her pretty well," Bucky says, marking the hole in Tony's story.

Tony's eyes slide in Bucky's direction, "Yeah, well, Rhodey came with me to my parents' funeral for moral support and Cas and I didn't really care at the time," Bucky flinches, "and Pepper only found out about her prior to me going public as Iron Man."

"Yet you never trusted us?"

"It's not my secret to tell, Rogers," Tony's voice takes on a sharper edge, "Rhodey and Pepper both found out through circumstance. I never told anyone. Trust me, it's a conditioned response. I don't talk about her. We keep in contact by hidden means, but I don't talk about her. To anyone."

"You still should have trusted us. We're your friends, your family."

"So was Obe!" Tony shouts, arm sweeping through the air.

The following silence is broken by Natasha this time, "Now it all makes sense," Eyes turn on her, "Pepper had gathered enough evidence to put Stane away for the rest of his life. No red tape, no possible loop holes for him to use. Stane would have been locked away and your comapny would have been back in your hands." Tony's fingers curl into tight fists when Natasha looks up at him, "Yet you killed him."

"Damn right I killed that greedy bastard. He knew she wanted nothing to do with Stark Industries. He was there the day she was born, the day she gave up the Stark name. And he still took her." Tony spits out, vicious in his anger, "I might be a selfish man, and I have a shit tonne of flaws, but nothing comes before her. Not my company. Not Pepper. Not Rhodey. Not even this fucking team comes before her safety, her security."

Tony looks away from Natasha and eyes the somber Captain, "So no, I don't talk about her. To anyone. And it isn't personal, not a slight against any of you. I still have my parents Will that states whenever she feels ready, she can take back the Stark name and everything that comes with it. She's twenty-five and not once has she wanted it."

"Ouch. Kinda harsh," Barton remarks.

Tony let out a rush of air, fingers combing through his hair, "No. She doesn't hate our family. She's spent so much time, building her own life and making a name for herself, that she doesn't need the Stark name. She wants the world to know her as she is, not because she's a Stark."

The tension is broken when Rhodes saunters back in, "Hey, Tones. Gorgeous is down for the count."

"I'm kind of surprised she didn't snag you as a pillow," Tony remarks.

"She was out before I even managed to get her shoes off. I just stayed long enough to make sure she was in it deep enough," Rhodes replies.

Tony's sighs once again, "Yeah. She's gonna need a new phone and tablet. I'm going to head down to my shop, see if I can pull up anything she may have backed up."

Without a second glance to his fellow comrades, Tony Stark left the room of shocked and somber heroes. Rhodes eyes the group for a brief moment before following after his friend.

"Anyone else find it amusing that some little slip of a girl practically deemed our illustrious Winter Soldier unimportant?"

Barton's snark earns him a cuff across the back of the head by his long-time friend and partner, Natasha.