I've been wanting to write Maddison for a while, but I couldn't think of a unique-ish situation to stick them in… So, I don't know, this idea popped into my head and kept asking and asking to be written… Bear with me.

What's in this fic, you may wonder? Well, I'm giving Addison a back story, for one thing (because I love to do that since the real show won't). I'm giving her a visiting relative who will have a big impact on her life and her future. Most of this will be Mark and Addison dealing with the situation this relative has put them in... That's my conflict, because I didn't want to write a bunch of fluff with no plan… So, that's the plan. Read and enjoy. :)

I own nothing, I make no money off of my creative writing, so please don't sue. The title is taken from Simple Plan's song, "Perfect." Please don't sue for that either.

Scenario: Mark and Addison survived the 60 days, and have been sharing a penthouse for four months without any major problems… Until now. ;) Other couples are as stands in the series as of 3.19, minus Izzie/George because I think it's gross and I don't wanna deal with that drama.

Addison stood in the baggage claim area of Seattle-Tacoma International Airport, waiting impatiently for her sixteen-year-old sister that she had been told she had to pick up only 7 hours before. When their mother had called that morning and said that her sister was on her way out to Seattle to shadow Addison and learn about medicine for a few weeks of her summer vacation, Addison had been shocked. Her sister always seemed to be more interested in art than other areas of academia. And why hadn't her mother provided her with more warning?

She barely even knew her sister. After all, Addison had been twenty when Cadence was born and over four hours away from their hometown of Greenwich, Connecticut, attending Cornell. When she had attended medical school at Columbia, she'd been only forty or so miles away, but didn't have the time to stop by for visits.

Cadence was a mid-life accident baby, and she knew it. She was raised as an only child from the time she was eight, but grew up in the shadows of siblings that she barely knew, but was expected to live up to. Her half-hearted attempts at extra curricular activities and her struggling B-average were not impressive to parents who had also created the country's foremost neonatal surgeon and a leading NASA engineer.

Though it had been a while since she had seen her, Addison immediately recognized Cadence when she entered the baggage claim area, a Coach duffel slung over her shoulder. It's what Addison could have looked like in an alternate universe – one without braces. Her sister was of average height, with the same red locks that Addison had, but with their father's emerald green eyes instead of their mother's and Addison's baby blue ones. She was dressed plainly, in an oversized sweatshirt and a pair of baggy jeans. With some nicer clothes, which Cadence undoubtedly owned, she would be a knockout.

When Addison embraced her, something didn't feel right. Addison held Cadence back at arm's length, stared at her hard, and gasped when she realized what it was.

Her flower girl, her baby sister, was pregnant.

"You're…" Addison stumbled a little over the words. "You're pregnant."

Cadence was confused. "Mom and dad didn't tell you?"

"No…" Addison said slowly, still reeling from the shock. "They didn't. They said you were coming because you wanted to learn about medicine…"

"Medicine?" Cadence's jaw dropped and she laughed a little. "They told you that? And you believe them? Come on, you know I hate science."

"I thought it sounded weird, but it's been a year and half since I've seen you, and people change." Addison glanced down at Cadence's stomach again. "A lot, apparently… But why are you here, then?"

"They basically kicked me out." Cadence sighed. "They told me I could come out here and live with you for a few months, and they claimed you'd already said it was okay… Some kind of rehab from the perfect daughter, I guess. The other science geek is in Australia..." Cadence was referring to their 26-year-old brother, Bradford. "Something about researching helicopter rotor blades… I don't know. So, apparently, you get me. Lucky you."

Addison digested the information, but didn't know how to respond. The sister part of her wanted to scream and yell at Cadence. The OB/GYN part was sympathetic to the situation, and wanted to help her. She decided she would have to opt for somewhere in between. Cadence had made a mistake. Addison couldn't fault her for that – she'd made plenty of her own.

Addison's highly trained eyes quickly evaluated the bump while they waited for Cadence's baggage to circle around. "5 months?"

"Yeah. Maybe you do deserve the big bucks." Cadence quipped.

Addison ignored the comment. She spotted Cadence's Coach suitcase that matched her duffel circling toward them and swiftly grabbed it off of the baggage carousel. "Have you at least had pre-natal care?"

"No…"

"Okay." Addison willed herself not to be angry with her sister, or their parents. Had they learned nothing from the stories she'd told them for years? "It's fine. We'll go to the hospital tomorrow and get that taken care of." She paused for a moment. She had to ask. "How did it happen?"

"You're an OB/GYN, Addie. Do you need me to draw you a picture?" Cadence crossed her arms.

Addison slowly inhaled, trying to keep from being annoyed with her sister. Had she been this pissed off at the world as a teenager? Of course she had… But she could finally see why it had gotten on her parents' nerves so much.

"No protection?"

"The condom broke."

"When did you tell mom and dad?"

"Two days ago."

"What?" Addison whirled around and looked at her sister. "Two days ago? How in the hell did they not notice, all that time? And they just flew you out here... That was it?"

"Yeah…" Cadence shrugged. "They're not around to notice. They don't give a damn… Unless their reputation is at stake obviously…"

"Oh, Cady…" Addison's voice softened. "What did they say?"

"First, mom yelled at me for smearing her good name of 'Forbes,' then dad lit into me for ruining his good name of 'Montgomery.' Then, they both screamed at me for ruining their perfect affluent suburban image. I mean, can you imagine if the neighbors found out?" Cadence said dramatically, mocking their mother.

"Well, one of their neighbors is Donald Trump…" Addison pointed out with a slight smile.

"Like he's never had a scandal?" Cadence snorted.

Addison sighed, her gaze still fixated on her younger sister's distended stomach, even as they walked through the airport. "Cady, why didn't you call me? I could have done… Something. I could have had the morning after pill prescribed for you, since you're not old enough to buy it over the counter… I could have—"

"Why would I call you?" Cadence narrowed her eyes. "Oh, that's right. You're Miss – I'm sorry – DR. Perfect. That's what our parents think, anyway."

Addison sighed again. It was true, though Cadence was exaggerating it.

"Of course…" Cadence continued bitterly, "They always seem to forget that you had an affair, shacked up with the guy for two months, and got a divorce. But I guess it doesn't matter what you do to screw up your personal life when you make millions of dollars a year saving lives."

"Would you please stop with the sullen teenager act?" Addison rolled her eyes in exasperation.

"It's not an act." Cadence insisted. "I am a sullen teenager."

Addison took a deep breath. "Okay, I'm willing to work with you here, but kill the lip, Cadence Forbes Montgomery…" The three siblings had their mother's maiden name as their middle name. Cadence hated it, and Addison knew that. It was the best way she could express how serious she was about what she was about to say "Or I'll have you on a plane back to Connecticut so fast…"

"Okay, okay… Got it." Cadence mumbled sheepishly. "Sorry." Addison gave her shoulder a gentle squeeze.

"For someone with a musical name, you are not very harmonious, you know." Addison said as she opened the trunk of her BMW to put Cadence's suitcase in it.

"I hate my name anyway." Cadence griped.

"What do you like then?" Addison slammed the trunk shut.

Cadence thought for a moment. "Spaghetti. Oh, and art. That's about it."

Addison shook her head as they entered the car. "Well, I do remember that much about you."

It was a warm summery day, very unlike Seattle, so Addison put the convertible top down. Their twin copper hair whipped in the breeze and they rode in silence for several miles, with Addison wondering how Mark was going to react that they suddenly had a houseguest – and might for a few months.

"Were you in love?" Addison finally asked, lightly drumming her fingers against the steering wheel as she drove.

"I thought I was… But I guess Anthony didn't feel the same way… He ran the moment he found out." Cadence stared to the side and watched as the foreign city whizzed by her. "I guess I'm too young to love someone."

Addison cast a side glance at the young woman, and then concentrated on the road stretched out ahead of them. "You're not too young to love someone… You're never too young to love. But yes, you will find that it changes as you get older… A lot."

"What am I going to do?" Cadence whispered, absently placing a hand on her stomach. For the first time since she had arrived, she seemed vulnerable. "What should I do, Addie?"

"I can't answer that… You'll have to decide that for yourself." Addison replied honestly.

Addison wondered if she should tell Cadence about her abortion. She tried, but she couldn't seem to force her lips to form the words.

Thoughts? There is always method to my madness. :)

Next, Mark is re-introduced to Cadence, and shares a secret with Meredith.