Notes: Continuing where 17 left off, on Day 2/3 of "The Mistress Always Spanks Twice."

Check out the AU twist to this story called "Whatever You Want." It includes the previous chapter and part of this one, and then veers in another direction.

Part Eighteen: On to the Affair

She wasn't as hard on anyone as she was on herself. She hung around a bit later at the precinct, beating herself up about not staying one step ahead of the suspect, but eventually she needed to yield to the fact that she couldn't camp out in the bullpen all night, waiting for Lady Irena to turn herself in.

Beckett went home.

Being a Smart Ass Masochist wasn't really working for Richard Castle. Sitting alone in his loft, his own little corner of SoHo, he came to terms with this.

Two factions were warring inside him.

First there was the part of him that refused to let Kate Beckett go, the part that couldn't do so if he tried. He wanted to be with her, and not just be with her—entwined with her limbs in all their lithe glory—but to be with her, to stand by her, to keep her company even in her missing-suspect misery.

Then there was the part of him that refused to disrespect her wishes. Wanting to be with her didn't seem to be a good enough excuse to inflict even more misery on her, to make her feel either ignored or unheard altogether. He didn't want to prove that he was just as selfish and inconsiderate as she ever believed he was.

Do whatever you want to do. You always do, anyway.

It was the first time in a long time that he thought of that fight at his book launch, back in the fall.

His complete and total failure to figure out what he really wanted, let alone to tell her; the way he only infuriated her somehow instead. The furrow in her brow as she provoked him in kind. Neither one of them actually saying much of anything. The torrid dance that accomplished nothing but driving them away from each other.

They had worked through that on some surface level—never to any great depth or detail—but it seemed like an awful lot of pointlessness in hindsight.

And he had a point to make.

The knock on her door was crisp; the rhythm vaguely incomplete, as though interrupted. She knew why when she opened the door to reveal Castle shifting a brown paper bag in his arms. It was haphazardly wrapped in a white plastic bag with a big yellow smiley face printed on the front.

He offered no greeting; only explanation. "Handles broke."

She noticed them and nodded dumbly, still making no move to beckon him inside. "Chinese food," she said, as though he needed her to tell him what hot, steamy thing smelled like that and came in a bag with a smile.

"It's the future," he said, voice equally informative, face still deadpan. She'd said for future reference. She never said when.

"Yeah," she agreed, but before she could make up her mind about how this was going to go, he was already walking past her and setting the bag down in the kitchen, stoically relieving both the weight and the burn of his hands.

His relief was subtle enough that she wouldn't have noticed it at all if she hadn't been watching so closely; still poised at the open door as though she might actually kick out a hungry, wounded gift-bearer.

She wasn't unaffected at the sight, but she showed no sympathy, either. Likewise, she didn't order him to go, but she wasn't exactly playing hostess.

It wouldn't have mattered; he made himself comfortable, shrugging off his coat.

Without saying so, she tried to rub in the fact that coming over uninvited and without calling first was dumb on his part, even if he wasn't entirely unwelcome: "What if I'd still been at the Twelfth?" she asked.

"But you weren't," he replied, effortlessly retrieving her silverware as though he did this every night.

She spoke over the untimely grumble from her gut, woefully reminding her that she'd neglected herself tonight; that he'd been right not only about where to find her but also about the state of her stomach. "But what if I was?"

"Then the food would've gotten cold by the time I found you."

No conceivable response could have thrown her off the way that did.

The idea of him going through the trouble of pursuing her, trying both her apartment and the precinct, just to bring her Chinese food?

It wasn't like she would have expected him to wait endlessly at her apartment door to surprise her. She just would have expected him to give up or go away or—not to have tried at all.

In fact, she'd told him not two hours earlier to go home. What the hell was he doing here?

Even as he pulled out a few takeout containers that smelled like salvation, she allowed the venom to surge back up inside her and asked pointedly: "And what if I'd had company?" She did her best to make it sound like that actually could have been a possibility.

But he didn't miss a beat. "Then you would've had to fight for the second fortune cookie."

At that, she rolled her eyes and shut the front door, seizing the opportunity to hide a trace of an unbidden smile, and joined him in the kitchen.

She was stuffed.

Only for one moment did she hesitate when Castle asked if she wanted the last steamed dumpling. Thinking better of it, she waved noncommittally at the container in his hands. "You can do the honors."

Fork poised over the dumpling, he met her eye. "You're sure?"

"Positive."

"But you would tell me if you did want it." It wasn't a question, and since he didn't seem unsure, she couldn't tell why he was still looking at her the way that he was. "You just had enough."

She gave him a funny look right back and promised, "Yeah. I know my limits."

He speared the dumpling before reaching for something else altogether. "Then I guess you won't mind if I take your fortune cookie," he said, popping the dumpling in his mouth while fingering the clear wrapper.

"Oh, no. Drop the cookie," she ordered as though it were a weapon. The little panda bear depicted on the wrapper smiled back at her. "You can have the fortune. I have no use for that."

"No, that's the rule," Castle said around his mouthful. He swallowed the last of the dumpling as he kept the cookie out of her reach. "You eat the cookie, you lay claim to the fortune. Unless, of course, you changed your mind and I can have it. . . ."

She leaned in more than he expected she could—seriously, just how flexible was she?—and snatched the wrapper. "Not a chance."

He picked up the second fortune cookie. "You ever add 'in bed' to the end?" he teased.

"You can't take anything seriously, can you?"

"Actually, Alexis and I usually add 'with zombies' instead, but—wait. Are you telling me you want to take fortune cookies seriously?"

Wordlessly, she conceded the point.

He would have helped himself to a tally on his scoreboard, but he was too engrossed in the moment to remember it; he wanted to continue the conversation before Beckett had time to feel uncomfortable in the silence. "You know these wouldn't even sell in China?" he asked. "They were based on a Japanese recipe before they became a Chinese-American thing."

"I think I read something about that in The Joy Luck Club," she said. It had been a while, but a classic story about mothers and daughters was hard to forget, not to mention an insight about one of her favorite kinds of food.

He nodded. "Blame the American appetite for 'vaguely Asian' stuff."

For the first time in months, Beckett thought of Danishes. She could no longer remember what they'd been called when they were named for Vienna, let alone the name of the original Austrian recipe.

No matter how many times she'd read Heat Wave, she still remembered who she was. And even at times when she'd been unsure—after the Halloween party, and after Coonan died—it was none other than Castle who had reminded her with no more than a gentle brush of his fingers and the soothing words, "Now you're yourself, Kate."

He knew her so well.

Again Castle broke the silence; roused her from her thoughts, fiddling with the wrapper. "I'll show you mine if you show me yours," he promised, waggling his brows.

She shook her head as though trying to be disappointed in him. "When has that line ever worked?"

"Hey, anything's possible except for me driving," he reminded her, holding up his naked cookie. "Last call. You in or out?"

"Fine. Yeah." She discarded her wrapper.

He unfurled his fortune and read aloud: "A friend will be important to you and your forthcoming success."

"In bed," she added when he didn't; teasing him a little too easily before realizing why he had hesitated, why a new expression had washed over Castle's face from the fortune alone. Something like recognition, gratitude.

She had wondered as recently as Christmas, but she didn't need to wonder anymore. He considered her a friend. Even after she chewed him up and spit him out tonight, it didn't change how he saw her.

A friend. If she was instrumental to his success, it was not simply as a muse. She was sure of that.

His own moment of genuine humility had caught him by surprise, but as he recovered, he had the good sense not to comment on forthcoming success in bed; in fact, found a way to laugh off the whole fortune. "Mm. Wonder which of my friends is going to help me fend off zombies," he said. "I hope it's Joe Schreiber. The only thing better than zombies is space-zombies." Then he crunched and chewed and nodded toward the unbroken cookie in her hand. "All right, give it up."

Without any trace of reluctance or dispute, she broke it in two and pulled away the pieces, but she had no sooner opened her mouth to speak before she shut it again. Her brow furrowed ever so slightly, and Castle made a sacrificial decision on the spot.

"You don't actually need to." Admittedly, it wasn't that selfless a sacrifice; it served to prove what he came here tonight to prove: that he would push her, but he wouldn't push her. He would keep redrawing her line, but he would never intentionally cross it.

It wasn't that he actually believed there was anything so personal about a mystery fortune from a takeout restaurant; giving it to her to keep to herself just seemed like a fairly simple way to make his point.

"Oh?" came out of a strangely dry throat. Without the presence of mind to swallow, she tried to compensate by licking her lips. "And what's the penalty for not going through with a deal?"

She still heard it in the back of her mind: We made a deal, and I expect you to honor that. She knew she'd considered them to have moved past that point, going so far as to ask him to walk her home from Remy's in spite of their bet, but part of her was still waiting for the day that Castle would throw her terms back in her face.

"No penalty," he said. She had gone into it willingly, and that was something. He only shrugged and told her, "Circumstances changed. A deal isn't a deal anymore if one person has to force the other. So if you won't share, I won't make you."

"Good," she said, ignoring his less-than-subtle subtext and rallying back to a place of superior confidence, "because I wasn't going to."

"Sure you weren't." He smiled and stood, scooped up the wrappers from the cookies and tossed them in the paper bag, cleaning up after them as a courtesy to his companion.

Then came the part of the evening he'd planned all along, and just when he'd started to feel like he wasn't going to be able to go through with it, this fortuitous conversation had encouraged him.

He made himself the first to say good night.

He did it gently, lightly, letting it come across as simply time to go and not like she had chased him away.

In order for his plan to work, she needed to sense that the decision was his and his alone; that it wasn't a ploy to play hard-to-get but an active choice to respect her time and space. She needed to see that he knew her unspoken wishes well enough to fulfill them; that he knew her implicit boundaries well enough to adhere to them; that what he didn't know, he would gladly learn.

She had to realize that he had redrawn her line—invited himself into just a little bit more of her life than she thought she could manage—and agree to meet him there and only there.

And for a moment, he was afraid that she was going to destabilize them; that she would not be able to relinquish the power of drawing; that she would take a step back or a step forward just to stay in control. If she took a step back, there was no way to know whether she would ever come to trust him. If she took a step forward, he wasn't sure that he could trust himself not to take another too soon.

Whatever he may have wanted, he needed her to yield.

She did.

Once he had gone, Kate succumbed to temptation to read the little scrap of fortune again:

"Conquer your fears or they will conquer you."

Was there nothing in the world that didn't come down to power?

The cabin was soon warm and aglow with a fire in the fireplace, a haven of privacy and heat even as the snow began to fall heavily outside.

By the time they stripped down to their underwear, Nikki had Rook right where she wanted him: flat against the bed beneath her, at her mercy. She wanted him to know just how much at her mercy he was.

She was still kissing him when she palmed the head of the bed and blindly located the leather cuffs she'd hidden there. She gave him a sassy smirk and buckled one around his wrist. They'd be secure enough that they wouldn't give even if he struggled against them.

But Rook didn't put up a fight. As she worked adeptly on the second cuff, he only grinned and said, "You've done this before. And not just as a cop."

She liked to lead, and she was enjoying his restraint. "And you can tell," she said, sounding equally unsurprised as she finished securing the two cuffs with a snap hook at each connection point.

"So I guess that makes two of—"

She didn't let him say "us."