When you spend most of your young adult life reading every word of the Journal of the American College of Cardiology and Heart - as Cristina Yang has - there really isn't much room left to prepare for detours.

Then again, Cristina has had her share of events that she could not have seen coming. Like the brief and unintended pregnancy while she was with Burke.

And meeting Owen, who, simply by being himself, would lead her to discover parts of herself she never knew existed.

Serendipity can be a blessing.

Monday morning, two days after Owen flew Cristina to Lopez Island, starts off innocuously enough.

Cristina showers, puts on a change of clothes and gets ready to brush her teeth.

She opens the cabinet under the sink, looking for - and finding more than an extra tube of toothpaste.

She sees the sentinel.

An unopened box of tampons ­- a box she bought more than two months ago.

Her mind had been so occupied with studies and clinical trials for treating metastatic melanoma and of course, Owen, that she had not noticed that she had missed her period last month, and it seems, this month, too.

Oh. My. God.

Owen.

Shit. Shit. Shit.

They had made love only that one time. It couldn't be.

Cristina's period had never been regular to begin with. But even for her, two months is a record.

She brushes her teeth quickly, her heart pounding so loudly against her chest, the sound might as well be drums in her ears.

She stops and stares at the mirror when she remembers the moment Owen climaxed with a deep groan, just moments after she herself stifled a moan as she reached her own peak of pleasure.

She knew all along that he would not be the type to think of his own enjoyment and satisfaction first. He probed, he sought, patiently, intensely, until he found the places that made her body tremble and shiver with ecstasy.

And afterward, he ran his fingertips lightly across her skin, caressing every line, every curve, every valley, while the blue seas of his eyes paralleled the navigation of her body and face, as if committing every inch of her to memory.

Weak in the knees, she pauses before she puts down the toothbrush and rinses. She looks at her reflection, thinking about how other men – including Owen – had told her she was beautiful. But with Owen, it is entirely different. From the beginning, she felt beautiful almost every time he looked at her.

She grabs her purse, heads out to the nearest pharmacy. She buys two early pregnancy test kits and heads to work.

But Cristina never gets the opportunity all morning to take them.

Instead, by a combination of sheer force of will and circumstance, she spends a good part of the day working with Dr. Dixon on a woman in labor with a rare heart condition. The irony of the situation isn't wasted on Cristina, who reminds herself that cardiology still is her number one passion and that she can't be distracted by something that she doesn't know with certainty. And being in Dr. Dixon's service unintentionally but conveniently keeps her away from Owen until she collects her thoughts.

She pores over the patient's echocardiogram and other tests when Dr. Dixon walks into room.

"Dr. Yang, what do you think?"

"You're asking me, Dr. Dixon?"

"Yes, I am. I think you know what's wrong with our patient's heart."

"Um, well, she has peripartum cardiomyopathy."

"Peripartum cardiomyopathy. A form of dilated cardiomyopathy in which no other cause of heart dysfunction can be identified. A rare disorder in which a weakened heart is diagnosed within the final month of pregnancy or within 5 months after delivery and can complicate 1 in every 1,300 - 4,000 deliveries. Hmm. Are you sure?"

"Perfectly."

Cristina says this simply, but confidently.

"Good. You may scrub in, Dr. Yang."

Hours later, there is nothing that feels sure to Cristina when she sits on a bed in the on-call room, arms folded over her bent knees. Meredith opens the door and leans inside.

"What are you doing here? Owen's been looking for you."

Cristina looks at her, but doesn't say a word.

Meredith walks in and sits next to her.

"Are you two okay? Please don't tell me he's back to having nightmares."

"No, it's not him. He's doing great."

"What is it, then?"

"Promise me you won't kill me."

Meredith's eyebrows furrow.

"What happened?"

"I might be pregnant. I haven't had my period in about two months."

"What!?"

"I know. I know. Don't get mad at me. I should've been paying attention when I suddenly started hating the smell of Callie's coffee."

"Callie doesn't exactly make the best coffee, so that could be nothing. So, did you take the test yet?"

"No. I've got two of them here."

"So? What are you waiting for?"

"I don't know. I don't know."

"Look. You shouldn't be worrying about it if you don't know the answer. C'mon. Start peeing and I'll look at the sticks if you don't want to."

Wordlessly, Cristina heads to the ladies' room, takes two tests, hands them back in a brown paper bag to Meredith in the on-call room.

"Do you want to talk about it?" Mer asks.

"No…. damn it. Why do those things take forever?"

"Cristina, you've missed your period before. You're probably just stressed out from everything that's happened to Izzie and Owen. And to you."

"I didn't want to be pregnant - the first time around."

"When you were with…"

"Yes, you can say it. Burke."

"I know. You would have had a smart baby with crappy DNA, like I will in a few years."

"What's wrong with my DNA?"

"Not yours. Burke's. The way he treated you. He thought he loved you. But I don't think he did. I mean, who does that, running away like a coward?"

"Burke." Cristina answers, smiling sarcastically.

"Exactly my point. Anyway, you have nothing to worry about."

"How do you know Owen doesn't have crappy DNA?

Meredith speaks more gently when she replies, "I mean… you have nothing to worry about because you're not pregnant, Cristina."

"I'm not?"

"No," Meredith replies, handing her the pregnancy test sticks, the minus signs unquestionable. She smiles and gets up to leave.

"Anyway, you can stop hiding from Owen now."

"I'm not hiding."

Meredith says nothing and closes the door.

Cristina waits for the feeling of relief to wash over her. But it doesn't come.

To her growing surprise, she feels pangs of regret.

She is not pregnant with Owen's baby. But it strikes her – no, shocks her - that she would have wanted to keep the baby if she had been.

And there could only be one reason for that.

She knows it now, as surely as the swift but strong rhythm of her heart.

Cristina bolts out of the on-call room and walks quickly, looking for Owen, spying him at the end of the hallway. He sees her and smiles.

Now or never.

She inhales and lets out a deep breath. "I need to talk to you," she says urgently.

"Now?"

"Now."

They walk together without a word to the boiler room.

Once Owen closes the door, Cristina walks to the other end of the room.

"You know how you once thought you would marry Beth? I almost got married once. He didn't show up on our wedding day."

"Cristina, I'm so…" Owen begins to say, his face pained.

"No, don't say anything. I need to finish this."

"He did me a favor. I thought that if I went through with it, I would love him. Now, I know I would not have felt that way. I loved cardio, Owen – I still do. He's a cardiologist. He symbolized everything that I wanted to be. I didn't love him."

"But you. You stitched me up. You did this to me. You made me love you. I-I-I love you, you hear me? I love you."

Owen closes the gap between them and kisses her deeply and passionately. When he stops, he brushes away a tendril from her face like he often likes to do and says,

"Cristina, I love you. From the first time I saw you here. I could have gone to another hospital after I came back from Iraq. But my heart told me to come here. I chose you."

Cristina answers softly, "And I choose you."