Author's Note: So, if you're new to my stories, the first note here is that this is in fact the sequel to my other Steve/OC story, Bohemia. There are a lot of references to events that took place in Bohemia, so I do recommend that you go through that story first so that you can understand everything that's happening here. :)

If you came over here from Bohemia, welcome! Idiosyncrasy starts up about two months after Bohemia ended, and starts at the tail end of Steve and Mack's road trip. I have a plan to release a one-shot about that road trip sooner or later, but certain events that happened during that road trip are going to be explored throughout this story. There's going to be a lot happening in this story, though I'm honestly not sure about the length yet. It might end up being around the same length as Bohemia, if everything works out.

And also, since it is mentioned in this chapter in particular, Steve does have his haircut from Winter Soldier as of Idiosyncrasy, if only because it is my absolute favorite of his hair. His hair gets better every movie, I swear.

And one last shout-out – we can thank HeartNimbus for the gorgeous cover image, for both Idiosyncrasy and for Potential! Thank you so much, my darling, and I hope that you enjoyed the first chapter for both stories!

I don't own anything related to the Marvel Cinematic Universe or its character. I only own my original characters and plotlines, which this story will have a lot of. There's going to be a lot of appearances of Captain America characters though, but I think you'll be surprised about who turns up in this chapter alone. Thanks again for reading and joining me on the next chapter of this series, and please leave a review on the way out!


Idiosyncrasy
Two months after New York, as they figure out their relationship and place in a new world, Mack and Steve find themselves in the middle of a conspiracy that threatens all they hold dear.


Chapter 1Down the Road


July 1, 2011

Mack Donahue had never felt quite comfortable at the SHIELD operations academy.

She had never been a student there. From the moment that Clint Barton had dragged her into SHIELD and a life that she was not prepared for at the least, Mack had been an abnormality in what was admittedly an organization of abnormalities that dealt with abnormalities. Repetitive, but it made sense to her.

Going to the operations academy with the one of the most motley crews that even she had ever dealt with, however, was something that she had never expected. Then again, what they were doing was also on the list of what Mack had never expected before.

"Alright, three, two, one… go!" Mack ordered, grinning as she glanced up in front of her.

The blond super soldier in front of her rammed into a waiting bulldozer, grunting sharply as he pushed it forward. The dirt spat up as the bulldozer was moved forward, surprisingly fast as Steve Rogers pushed it. Though it wasn't always completely noticeable, Steve's super strength was absolutely incredible, especially when it was put on display like this.

Mack started the stopwatch in her hand the instant that he moved, raising an eyebrow as Steve moved it forward surprisingly fast, using every bit of super strength that he had in him. The ending point was a few dozen yards away, and Mack waited at that finish line with three other men, all of whom looked incredibly interested in this.

"Whose bright idea was this?" Gabe Jones asked, looking back down at the stopwatch before turning back to the super soldier and the bulldozer.

"Who cares? This is amazing!" argued a young man around Mack's age with a striking resemblance to Gabe, especially in the cheekbones and eyes. It would have been cleared to any stranger that they were related.

"Got to agree with your grandson, Gabe," Dum-Dum Dugan admitted, raising an eyebrow over at his old war buddy before turning his attention back to the war buddy currently pushing a bulldozer across a training field. The remark drew a grin out of Antoine Triplett, Gabe's grandson. "Besides, who hasn't wondered about who would win in a fight between Steve and a bulldozer?"

"I've wondered about Steve versus a T-Rex, but never a bulldozer," Mack admitted, laughing for a few moments before turning her attention back up to Steve.

With a final yell of exertion, Steve pushed the bulldozer far past the finishing line, his breathing actually heavy as he stopped. His hands rested on his thighs as he bent slightly, breathing heavily as he mopped the sweat off his forehead. This test had actually pushed him, and every person there knew how much Steve would appreciate that challenge. Mack had ended the timing on the stopwatch the second that he had crossed the finishing line.

"Time?" Dugan asked eagerly, leaning over to pull the stopwatch out of Mack's hand. His eyes widened before he looked at Steve, laughing. "Son of a bitch…"

"What?" Jones demanded, pulling the stopwatch over himself. He raised an eyebrow, shooting an amazed look at the panting Steve. "Jesus, Captain."

Mack was near hysterical, her arms around her middle as she laughed. "No one's going to beat that time, even with super strength" she said, grinning as she winked at the approaching super soldier. She tossed the stopwatch at Steve, who caught it without looking. "You just set an unbeatable record there, babe."

The super soldier frowned as he looked at the time, his gaze flying back to the bulldozer. "I can beat that time," he said, scowling as Dugan handed him a water bottle, thanking him quickly before taking a sip of it. "I can put it back, wait a few minutes, and then try it again-"

"No, not happening," Mack warned, swatting his arm and rolling her eyes. "We're on vacation, Steve. Enjoy being on vacation before you have to go meet my family."

"Enjoy being on vacation while I'm back at Culver teaching summer courses," Jones added, patting Steve's arm as the group of five made their way back over to the SHIELD base. "You're both still going to come and visit in September, right?"

"Are you kidding? Of course," Mack replied, smirking. "I want to see Culver. I need to go annoy the people in the psychology department. I especially need to go annoy Samson if he's still there."

She also needed to go take covertly check up on Betty Ross, though she didn't plan on mentioning that part to Steve until after the fact. Mack hadn't had contact with Bruce for nearly a month, though it wasn't too surprising. Despite having SHIELD watching his back a bit, Bruce had unsurprisingly decided to keep to himself, though Mack knew that Bruce and Tony were in constant contact.

The Avengers themselves had been disassembled for the time, but they were still in contact, still ready, just in case. The months since New York hadn't been the easiest. Clint and Natasha were back in New York at least, now living in the apartment that had been Mack's. While Clint's mental state was still a bit debatable, he was a thousand times better than he had been months before.

"And I want to see you teaching kids, Gabe. It has to be interesting," Steve added, putting an arm around Mack's waist. She rolled her eyes slightly, but smirked at the contact.

"You'll be able to visit more often, at least," Gabe pointed out, nodding. "Somehow the fact that you're moving to DC doesn't surprise me that much."

Mack shrugged. It didn't surprise her too much either, honestly. "SHIELD transferred me to the Triskelion after New York. We didn't exactly get a choice in the matter."

Mack had warmed up to the transfer over the past two months, as had Steve in some ways. The move down to DC was going to give them both a fresh start –with Steve now officially signed on as a consultant with SHIELD and Mack not quite back as a full-time agent, DC would give them a new start professionally and personally, despite the fact that they were surprisingly stable as a couple for the moment. They were honestly taking every day as it came, hoping that they were going to be able to handle everything that was thrown at them.

Trip turned over to Dugan as they made their way into one of the gyms of the operations academy, a questioning look on his face. "How's Tori doing?" Trip asked, glancing over at Dugan.

"Exhausted and getting bigger by the day," Dugan replied, wincing slightly at the thought of his very hormonal, increasingly pregnant granddaughter. "Sam quit SHIELD. His heart was never in it though, after what happened in Pararescue… he joined for Tori. They're both in Boston until the baby's born, continuing the Dugan family tradition that you're either born in Boston or suffer ridicule as a Dugan."

"The baby's also a Wilson," Steve pointed out. He hadn't met Sam yet, though he knew that it would probably happen sooner or later, especially considering the fact that they were planning on heading up to Boston for the birth to be there for Tori.

"The terrifying combination of Tori and Sam's genes that his father and I have discussed many times over," Dugan corrected, shuddering slightly at the thought.

Mack couldn't help but agree with that, especially considering the fact that she had seen Tori at her most angry before. She glanced over at the boxing ring as she raised an eyebrow, seeing the fact that the gym was completely empty at the moment. She thought for a few moments before glancing over at Trip, since she knew Steve wasn't in the shape for a spar at the moment.

Trip seemed to be thinking the same exact thing. "You're on, Donahue," he said, a challenge clear in his eyes as he pulled off his jacket, hurrying into the ring without another word.

"You're going down, Triplett," Mack laughed, sliding into the ring a few moments later.

Gabe raised an eyebrow, leaning in towards Steve. "So, does my grandson stand a chance in hell against her?" he asked in a low voice, laughing as he watched the two circling each other, Mack pulling her dark hair into a tight ponytail. Both were clear professionals, and this promised to be a serious fight.

"Not at all," Steve confirmed, grinning at his old friend before patting him on the back.

He turned his blue-eyed gaze back to the two, smiling slightly as he watched Mack lunge at Trip, launching herself off the ground and into a strong kick, landing on both feet as Trip stumbled back. Mack's style was unpredictable at best. Steve had learned that through various sparring sessions, though ti was even clearer now.

The specialist dove back at her instantly, managing to grab onto her from behind. Mack flipped, grabbing onto his shirt and pulling herself up, her legs going around his neck as she brought him down again, pinning him to the ground. Trip tried to get out of the leg, groaning as he finally slammed his hand down on the mat.

"I give!" he groaned, glaring up at Mack. The brunette smirked happily, pulling her legs off of him as she got to her feet, shooting a victorious grin over at the remaining Howling Commandos.

"My grandson," Gabe pointed out dryly, far too amused at the situation.

Steve's grin was only proud and loving. "My girl."


It was just before they were going to head back out on the road when Mack grabbed Steve's arm, pulling him through the deserted halls of the base. A couple of the cadets had stolen Arizona for a while earlier, and they still needed to pick him up. The opportunity to play with a fluffy animal was too much even for potential SHIELD agents, apparently. Mack had taken advantage of that to take Steve away for a bit, claiming that there was something that he needed to see.

"Where are we going?" Steve demanded. He hadn't put up a fight when Mack had pulled him out of the room where they had been observing a training session, instead just looking around the SHIELD facility.

It was fascinating to find out that this organization had grown from an idea that Peggy, Phillips, and Howard had come up with together. He had learned a lot more about the history of SHIELD since after the Battle of New York, and Mack had been able to fill in some of the gaps. He knew that if it weren't for Peggy helping to found it and Mack being a part of it, Steve wouldn't be anywhere near SHIELD.

"It's a surprise, but I know you're going to like it," Mack promised, raising an eyebrow as she stopped them in what appeared to be something of an atrium. There was a display in front of them, the SHIELD symbol engraved above it in black marble.

"The Wall of Valor?" Steve repeated, frowning as he stepped forward, taking a better look at it. There were names written on it, dates up above.

"A memorial to the agents lost in the line of duty. It goes back to the very beginning of SHIELD," Mack explained, standing a bit away from him, looking at one of the most recent additions to the wall. Her name traced Phil Coulson's name gently as she glanced over at Steve. "Look at the earlier ones."

Steve nodded, heading over and looking down at it, starting from the absolute beginning. A name or two were familiar at first, until he found one that was more than familiar. Steve froze at the name for a few seconds, not sure if he had misread it. He read it over a few more times, trying to find the words he needed to speak.

Mack waited patiently, her finger still resting on Phil Coulson's name. She understood loss, and she understood the loss of one of the most important people in your life. She knew that Steve was going to need a few minutes to adjust to what he had just seen. Steve looked over at her, blue eyes wide with surprise.

"Bucky," he said simply, shooting an amazed look at Mack.

Mack stood up and straightened, sighing as she leaned against Steve's arm, squeezing his hand. "From what I've been told, Peggy had his name added as soon as SHIELD was founded," she explained, nodding at a blank spot above. "Your name was there until you were found in the ice."

Steve crossed his arms against his chest, staring down at his best friend's name for a few moments. "He would have liked this," he murmured, looking at his feet for a few seconds. "Complained about it nonstop, but he would have liked it a lot."

She managed a weak chuckle, knowing how hard it was for him to talk about Bucky, even now. Mack nodded slowly, looking back at him. "I wished I could have met him," she said, glancing back up at him.

Steve bit his lip, looking down at her, wrapping his arm around her shoulder. "The next time we're in New York, I'll take you to his grave," he murmured, looking back over at her a moment later.

She raised an eyebrow in surprise. "You're sure?"

"Very sure," Steve promised, kissing the top of her head gently, managing a soft smile. "My best friend needs to meet my girl somehow, right?" He knelt over, kissing the top of his head, his lips lingering at her hair for a few moments. "Until then, we have something important tomorrow."

Mack scowled instantly. "Fuck."


July 2, 2011

"You don't have to do this."

"Yes, I do."

"You really don't."

"It's okay, I want to."

"Seriously, babe, we can turn around right now, spend your birthday on Coney Island…" Mack played lightly with the silver charm bracelet around her wrist almost unconsciously. She stared out the window, half exhausted and half exasperated. "It'll be better."

Steve laughed again, shaking his head as he looked over at his girl in the passenger's seat. "I want to do this, doll."

As she leaned her forehead against the glass window of the jeep, Mack didn't bother glancing back over at her boyfriend in the driver's seat. "You really shouldn't," she replied quietly, pulling her long dark hair back into a ponytail.

Steve chuckled, shaking his head as he glanced over at her, keeping an eye for the exit that they needed to get on. "It's meeting your family, Kenzie, not a suicide operation," he pointed out.

"It's basically the same thing," Mack protested, scowling as she looked back over at him.

"With what we've gone through, meeting your family is one of the things I'm least worried about," he admitted, raising an eyebrow back at her as he kept driving. He had gotten used to driving Mack's jeep, though he did adore his motorcycle, currently attached to the back of the jeep.

"Oh, you naïve boy," Mack laughed, laughing sarcastically, taking a drink from the water bottle between them.

Steve's hand left the wheel to squeeze her knee gently, knowing that she was beyond nervous about this opportunity. "Tell me again who we're meeting."

She gave a deep sigh of exhaustion, closing her eyes for a few seconds. "My mom, my stepdad, my stepbrother and stepsister, and their families," Mack listed, looking over at Steve and raising an eyebrow. "My stepsister is pregnant with her second daughter, and my stepbrother has three boys. The boys are Neil, Craig, and Alec, six, four, and two, and the girl is Dahlia, who's three."

"Bridget's husband won't be there because of work, and Sean is amicably divorced from his ex-wife Laurel," Steve said, remembering the little tidbits that Mack had mentioned over time. "And you still keep in contact with Laurel."

"And where are they from?" Mack asked, playing serious as she smirked up over at him.

"Bridget lives in Pittsburgh with her family, and Sean lives in Philadelphia. Laurel and the boys live in New Jersey," Steve replied obediently, knowing that he had all of the information down pat. He had heard Mack talking about it enough of the last few weeks. "And your mom and stepdad Kevin live in Wrigley."

"Population no one cares and dropping," Mack muttered, shaking her head as she set the water bottle back into the cup holder between the seats. "You nervous at all about meeting my family?"

"Not at all," Steve replied. He was a horrible liar though, and he knew that Mack would see it instantly.

Steve didn't think that it was too unbelievable that he was nervous about meeting Mack's family, no matter the fact that he was Captain America and had met Mack's mentors, who were the two best assassins in the entire world.

Honestly though, what man wouldn't be worried about meeting the family of the girl he loved?

"You know, lying to a spy is one thing. Lying to a spy when you're so bad at lying in the first place is something else." Mack bit her lip, looking back over at Steve. "Do you think your mom and Bucky would have liked me?" she finally asked, half hating bringing up the question.

It was something she had wondered numerous times though.

"I know it," Steve replied instantly, shooting her a dead serious look. Mack looked over at him, biting her lip. "Ma would have absolutely loved you. Mack, my mother was… she was amazing. Strong and smart and sweet. She was beyond amazing."

"She raised you, of course she was," Mack pointed out. Her hand went to his knee, squeezing it tightly before offering her hand in the back for Arizona to lick.

She played with the silver charm bracelet on her wrist carefully, looking down at the seven newest charms on it – a bolt of lightning, an hourglass, an arrow, a tiny fist, a helmet, a star on a shield, and a knife. A charm for each of the Avengers. That was the family they shared, and Mack knew that nothing would chance that.

Steve hesitated. For a few moments, it looked like he wanted to say something to her, but changed his line of thought at the last minute. "You and Bucky would have either loved or killed each other," he admitted bluntly, laughing to himself. "You'd probably complain about sharing me."

"My Steve," Mack teased gently, laughing as she shook her head, glancing out the window for a few moments. The jeep was silent for nearly twenty minutes, and when Steve next glanced at her, she had that look on her face, the look that screamed that she was thinking about something.

"I know that look. What's on your mind?" the super soldier asked, raising an eyebrow over at the assassin.

"Nothing," Mack answered, immediately dismissing the question.

"Mack." Steve's voice was gentle, a lure to try and get her to open up. Even after a few months of a relationship, Steve still found that pulling teeth could be easier than getting Mack to talk.

To his surprise and satisfaction, she only gave a hesitant sigh. "It's weird. Everything's just really weird lately."

"What do you mean?"

"I don't know. Everything is changing," she admitted, closing her eyes as she leaned her head back against the seat, her hand reaching into the back to pet Arizona. "We're moving to DC in August. We had an alien invasion two months ago. The Avengers are pop culture icons. Everything is freaking weird." She shot him a mock glare. "And then you got your hair cut last month."

"I thought you liked it," Steve protested, shooting her a look. Mack had been joking that his hair was a lot more modern than it had been before the Battle of New York, and Steve personally liked his new haircut. His adjustment to the present had been smooth as of late, though he knew that there would be more bumps in the road sooner or later.

"I love it," Mack replied, rolling her eyes as she swatted his arm, putting her feet up on the dashboard as she looked back outside. "But still. It's just weird to see how everything is changing." She paused before wincing. "And here I am acting like a complete idiot because I'm talking to you about change."

"If anything, I understand what you mean," Steve pointed out, though he was relieved that she had realized what she had been talking about to him. He understood better than anything watching everything change around you. "What was it you called it? A brave new world?"

"Something like that," Mack hummed, sighing and closing her eyes before glancing out at the highway. "I'm so not ready to deal with my mom."

"She seemed nice whenever I talked to her on the phone."

"That's how she lures you in. With niceness and baked goods and all of that." Mack nodded sagely, shaking her head as she pulled out her phone. "Pull over on the next exit, we can find a motel to stay in tonight."

"Kenzie," Steve said, shooting her a warning look. "You know we have to see her soon."

"We can see her tomorrow!" Mack protested, shooting him a mock glare as she ran a hand through her hair. "Please, Steve, let me mentally prepare for my mother."

Steve shook his head, wondering just why she was so nervous about him meeting her family. He did take the next exit, keeping his eyes peeled for a motel. "I still say you're overreacting."

The brunette didn't answer him, and instead focused on getting a hold of her mother, finding success after a few rings. "Mom, it's me," Mack said, shooting a warn glare at Steve to be quiet for now. "I've got bad news. Traffic was really bad getting into Pennsylvania, and we're exhausted. We're gonna stop in a motel for a night, and we'll be there tomorrow morning."

He knew that this was something that they both had to go through. With how quickly they were getting serious, meeting Mack's family was inevitable for Steve. He just wanted to make sure that this went as easily as possible for both of them.

Arizona, meanwhile, would probably be lapping up attention from the children.

Steve rolled his eyes. "You really don't want this to happen, do you?" he asked, glancing over at her, unable to keep the concern off of his face. Steve turned off the jeep after parking it in a space in a motel parking lot, a place that looked slightly better than some of the places that they had stayed in over the last two months.

Mack hesitated before glancing back up at him, biting her lip. "I've worked incredibly hard at keeping my personal and professional lives as separate as possible," she admitted, shaking her head. She frowned. "Hell, I don't have a personal life, I just have friends from SHIELD. I met you because of work."

"You met me because a Russian oil team stumbled across the Valkyrie by mistake," Steve corrected, raising an eyebrow over at her as he got out of the car, heading to the trunk to pick up one of his bags. Arizona jumped out the back, nuzzling Steve's leg with a happy whine.

"And that up and away was the best mistake ever," Mack replied, smirking over at him. She walked over, kissing him quickly for a few seconds before shaking her head. "I'll get the room. We can just relax and I can mentally prepare for you meeting my mom."

Steve smiled softly as he knelt down, petting Arizona gently as he watched Mack walk towards the motel office. "It's not going to be that bad!" he called, glancing back at Arizona as

"You'll see," Mack retorted, pausing to walk backwards and glare at him.

Steve looked down at Arizona, laughing as the dog licked his face. "Yeah, bud, I agree," he said, glancing back at the office. "Kenzie can be a little crazy sometimes."

He loved her anyway.


Author's Note: As you can see from this, these two are absolutely more comfortable with each other now, and will be getting a lot more comfortable with each other as Idiosyncrasy goes on. I'm planning on introducing a lot of characters in this story, and a lot of plot threads, so I think you guys will enjoy where I'm planning on taking this story.

Thanks again for reading, and please leave a review on the way out! Next chapter will be a lot of fun, with the introduction of Mack's family, and Steve meeting said family. After that, we'll be going into a lot of other plot plans. There will be a lot of angst, especially in the beginning of the next chapter, a lot of drama, and of course, a lot of sarcastic banter.

It wouldn't be the Shiv series without sarcastic banter, after all!

I hope everyone enjoyed the beginning of this story! Since it is the summer, I'll hopefully be able to write as much as possible when I have the chance, though I am working full time as a summer camp counselor. I will try and update at least once a week when I can, though don't hate me if I don't update super quickly.

Thanks again for reading, and please leave a review on the way out! I want to see what you guys think of this chapters, of Gabe and Dugan and Trip appearing, of the inevitable introduction of Mack's family. I'll see you all next chapter, which is going to open with a bit of a bang.

Chapter 2 – More than Blood
"My nephew is a Captain America fan. This is beyond ironic."