Disclaimer: I use characters and some plot from both The Avengers and the new X-Men films. I didn't make this a crossover because I really don't mention any of the characters that much from X-Men aside from Beast but I warped the timeline from those films (the story is set shortly after Age of Ultron) and Peter/Quicksilver plot line never existed in this story. In this story Quicksilver is the Age of Ulron version. I obviously do not own The Avengers or The X-Men.

...

"I wouldn't care if the human world was falling into infinite peril and I was the only one who could save them. I'm not leaving you, Beast."

Closing his eyes, Dr. McCoy removed his glasses from his face and pinched the bridge of his nose. His office was already stuffy enough as the air was broken and this was about the fifth time that they had had this argument in three days. "I'm going to D.C., to fight for equal rights for mutants and humans. You don't even exactly support that, so you're not missing out on anything."

The young adult slammed down a blue book on the desk subsequently cracking its spine before her to capture Hank's attention. He reopened his eyes and rubbed his face in an exasperated fashion. "Why are you trying to get rid of me?" she shouted. Jet-black veins began to spread through her olive skin from below her eyes while her green irises turned furiously bright red and the white surrounding them flickered to the color of night.

Hank rose from his seat, running out of patience. "Kassandra. I need you to calm down and listen, really listen to me for once in your life. I am your family, and you couldn't get rid of me if you tried." Still seething, she dropped back down in her chair, just like back when she was in trouble as a pupil at Xavier's School for Gifted Youngsters. "I am your brother, your best friend, your teacher, your biggest supporter, frequently your greatest enabler, and sometimes your father. I will always be. As your guardian for those few years, I feel strongly that this is a new path that is going to bring you fulfillment, if not a little bit of happiness and peace as well. Joining The Avengers will be just like any other mission you've been on with the X-Men, just a little bit longer. But you're still going to come home to me, wherever I am. Come on Kass, tell me that you are happy with the other X-Men without lying. Imagine not having to work with Cyclopes every day!" He felt a little more relieved as he watched her fighting back the smile tugging at the corners of her lips as the veins began to slowly creep back. "Pretty great, huh? Look. I know that maybe the X-Men aren't your life calling and you put your best effort in for my sake. I accept that. I understand and accept your stance on mutant-human relations and I accept that you don't have to be just like me. I wouldn't want you to be, because you are the best Kassandra Rose Thistle-McCoy that will ever be. But I do know that you hate HYDRA more than the innocent humans that they terrorize. And Doctor Banner needs you. Uncle Tony needs you."

Kassie rolled her now back-to-normal looking eyes at him, now that his heart to heart made it through the deep end and headed back into the shallows. "I haven't called Stark "Uncle Tony" in like four or five years. I'm an adult, and he's an asshole."

"You're an asshole. Ever wonder where you got that from?" Hank laughed, Kassie shook her head. "Stark never missed a Christmas or a Halloween. Who dressed up with you like Beauty and The Beast when you were fifteen and took you grown-up trick-or-treating? That one wasn't me."

"I just don't know what use I could possibly be to The Avengers. They're the best of the best. And maybe Banner doesn't want to be found. Who are we to say that he doesn't know what he's doing?"

"I don't know how you're going to help them. Maybe Tony just needs a friend for all we know."

"I'm a terrible friend," she groaned.

"No you're not. You're the best friend I'll ever have."

"You already said that," she pointed out.

Hank sighed and put his glasses back on as he sat back down behind his desk. "You know, Doctor Banner put your name forward to become an avenger two years ago, right around the time of your twentieth birthday. I didn't want you to go. I feel bad about it now. I was being selfish."
"Don't feel bad. I wouldn't have gone anyway," she muttered.

"Stark didn't think you were ready either. But he does now, and I do too. Bruce Banner and Tony Stark helped me save your life over seven years ago, remember that? They were there with me when you needed their help the most. I think you can do this tiny favor for them in return."
Kassie knitted her eyebrows together and scoffed. "Tiny?"

"Tiny. In the grand scheme of things," Beast smirked.

….

Steve Rogers stood at the end of the ramp that led away from the helicarrier as he watched his newest recruit descend. She was tall (her file said about five-foot-eight) but she was thin and willowy. He reminded himself that she had been a Captain of the X-Men at a young age so she had to be sturdier than she looked. She probably didn't do much hand-to-hand combat though, given her abilities, but she would still need to be trained on it given some of his past Avenger experiences. If Stark believed in her, and he rarely believed in anyone, then he believed in her too. "Welcome Kassandra," he said as she finally reached conversational earshot distance. He stuck out a hand when the girl reached him. "The name's Steve Rogers, or Captain America. Call me what you like."

She shook his hand with a firm grip. Good indicator. "Kassandra McCoy, alias is Voodoo Doll. But you can call me Kassie, Captain."

Steve smiled. "The rest of the team is in the living quarters waiting for us. Can help you with a bag?" he asked, gesturing to her backpack and overnight bag politely.

She shook her head no. "I'm okay," she smiled. It was only her laptop and an overnight bag, the rest of her stuff was in a truck being driven from Xavier's School to The S.H.I.E.L.D. compound and would probably be thoroughly searched through, knowing the government and their affection towards mutants.

Steve made small talk as they headed inside through numerous hallways and twisting corridors towards the central elevator. "Well, half of the team is here. Thor is in Vanaheim, one of the realms, dealing with some rebellion of sorts that is a bit out of our Midgardian league," he chuckled. "Agent Romanoff is with Fury doing recon related to finding Dr. Banner. Hawkeye is back home with his family at Walt Disney World, and War Machine is in D.C. working on a new pilot training program. But the rest of the gang is here. The others will be back in a few weeks when The Avengers "officially" reconvene."

"Am I the only one that will be living here?" she asked mildly confused.

"Of course not. Most of the team that you're about to meet lives here with the exception of Sam and Tony."

Kassie nodded her head, pretending to know who Sam was. She was better with aliases; it's basically all she used at Xavier's. She rarely called her best friend Storm by her real name. It just seemed weird. But the difference was birth name vs. a mutant's true self, as the Brotherhood put it. Here, there were a lot of frail humans with an alias, so she supposed could change her outlook a bit. Besides, they seemed to have longer names.

"Are you taking notes on how to find your way around?" Steve asked, pretending to be annoyed by her lack of attentiveness. Kassie looked at him wide-eyed for a moment before she realized that he was joking as the elevator doors closed. "Don't worry, you'll figure it out after you get lost enough. Or not. Pietro Maximoff has zipped up, down, and around these halls at least a thousand times and is still petitioning we hand out building maps to new recruits."

She smirked. "So don't ask that guy for directions, right?"

"You learn quick," Steve replied as the doors reopened. "13th floor, living quarters. Try to remember that one," he said as pointed to the number printed on the walls as they stepped into yet again another hallway. "Almost there."

The pair walked a few more yards before making an abrupt left at the first entryway they passed, revealing to towering dark cherry oak doors. Steve stepped ahead and pulled the doors back so she couldn't quite get a good glimpse until they had walked into the actual room on the other side.

"Whoa."

Steve looked at her gaping mouth as her eyes swept over the room. "I'm guessing it's a little more modern than the fortress that is Xavier's School."

"A little? This is state of the art compared to that old castle." Glass, chrome, and more glass. The entrance area was a giant platform with the center missing, revealing the floor beneath them in the open aired box shape. The ceiling was incredibly high and there was a set of stairs nearby. She could see the other side of the living quarters from where she stood thanks to her gifted eyes. Glass walls were across from her that held a corridor and from what she could see, two doors with dorm numbers on them. More hallways to her left and right. Downstairs a few people were lounging on brightly colored plush couches or playing cards in what seemed like a massive living room.

"You guys coming down, or do I need to fly up there in my super suit?" a familiar voice shouted at the pair. Kassie knew who it belonged to even if she wasn't close enough to the edge of the railing to see exactly who was beneath them.

"You could always take the stairs, you know," Steve shouted back walking towards them. "You can leave your bags up here, you can move them to your room when you're ready to head over there.

"Now what's the fun in that, Captain?" the voice bantered on.

Kassie laughed quietly. Perhaps she missed Stark a little.

"There's my infant Avenger," Tony said stepping into her sight line.

"That's a new one," Steve remarked.

Tony ignored his comment. "What, no running majestically into my welcoming arms kiddo?" The others looked at him with incredible skeptism apparent on their features as they began to gather around him.

"You couldn't even be bothered to meet me on the helipad because it was raining."

"Couldn't risk messing up my hair. You're a young woman, you get it."

Kassie rolled her eyes as she dramatically and dutifully dragged her feet across to the floor to give him an unenthusiastic hug.

"I can really feel the love right now," he said wrapping his arms around her. He pressed his face into her hair and muttered lowly. "I've really missed you, Kass."

"Yeah, yeah," she said, as they pulled apart. "You're going soft."

That got a couple of laughs from the spectators and a mirrored eyeroll from Tony. Okay, maybe she did pick up some attitude quirks in their brief time spent together, she thought.

The crew started to line up behind her as she began to take them all in. "This is Sam Wilson, also known as Falcon, so now you can stop pretending like you know who I'm talking about," Steve introduced his friend.

"Oh thank heavens you picked up on that," Kassie snickered with relief.

Sam looked at them strangely as he shook her hand. "Pleasure to meet you," he said, still unsure.

"Everyone, this is Kassie McCoy," Tony interjected.
Kassie shot him a look that said 'thanks-for-that,-but-I'm-an-adult-who-can-speak-for-herself.'

"I am Vision," said the man—er robot man thing—to Sam's right. "No other name."

"Nice to meet you Vision," she said now being the one giving strange looks. She made a note to ask what was up with him/it later.

"And these are the Maximoff twins," Vision said, gesturing to the pair at his side.

"I am Wanda, or um…Scarlet Witch they call me," she said with her thick accent taking her hand excitedly in both of hers. Kassie looked at her wide eyes, they were beautifully strange in person, not like on the television set they watched the Sokovia debacle on back at the school. "Kassie," she nodded at the Maximoff girl who released her hand.

"Pietro / Quicksilver." Her brother simply introduced himself with a small wave from behind his sister's shoulder. He didn't seem to be riddled with bullets, the up side of being a mutant.

"Ah, bad direction guy," Kassie said turning to Steve. When she looked back him his blue eyes looked vaguely disinterested but his mouth deceived him. "What's your super name?" he asked, ignoring whatever he had just missed.

"Voodoo Doll," Kassie replied, realizing that she had only told Steve before they entered the room.

He screwed up his face thinking momentarily. She looked at him, waiting for whatever he looked like he was about to say. She raised an eyebrow during the awkward silence. "I'm sorry…but what does that mean you can do?"

Kassie smirked. "I'll show you sometime."

Suddenly a bolt of pain shot through her head. Kassie grimaced and reflexively touched her forehead. Pietro and Wanda directly ahead of her looked very concerned.

"What is wrong?" Wanda asked.

"Nothing. Just tired. It was a long day of packing and goodbyes," she lied.

"Have you fed today?" Stark interjected.

Pietro wrinkled his face processing the strange English phrase. That's a strange way to ask if someone has eaten today, he thought.

Busted, Kassie thought. "No. I finished off my supply at the school last night. Hank said there would be a shipment from the manufacturer waiting for me here."

"There is. I took the luxury of stocking your mini fridge with it before you got here," Tony replied.

"We weren't sure if you'd want that stuff out in the open until you're comfortable here," Steve lowly added to the conversation. The three of them had gravitated close to each other while the others looked at them curiously.

"Thank you," Kassie said smiling faintly at both of them. "It's been a long night," she said turning back to the others. "I'll see you all in the morning…?"

"You need to rest up for your evaluation in the morning. It's way past your bedtime young woman," Tony scolded.

"Oh fuck off," Kassie laughed softly as she headed for the stairs.

"Language!" Tony shouted after her.

And now everyone was laughing.