Disclaimer: I don't own Castle. The only profit being made is my own amusement (and hopefully yours).

His Last Romance

Author's note: I'm going the by timeline that Poof You're Dead (3x12) happened before Nikki Heat (3x11).

Men always want to be a woman's first love. That is their clumsy vanity. Women have a more subtle instinct about things. What they like is to be a man's last romance.

—Oscar Wilde

By the end of his second case with her, Castle learns that Beckett has been in love before. He knows the hurt is real when he hears her tell Chloe, Guys can be like that. They can lie and I know when you find out how much it can break your heart. Logically, he shouldn't be surprised; he can't imagine anybody reaching the age of thirty without falling for someone else.

She intrigues him anyway.

Three minutes after Alexis kisses him on the cheek and saunters out the door to school, eager to show her pre-calculus test who's boss, Castle discovers that she's left her lunch on the counter. He's preparing to take the paper bag and catch up with her, but at that moment the doorbell rings. Of course his responsible Alexis would notice something as important as peanut butter and jelly on whole wheat bread.

"I've got it, pumpkin!" he announces as he swings the door open.

To his surprise, it's not Alexis but another redhead he finds standing in front of him.

"Good morning, kitten!" Meredith exclaims, pouncing on him and pushing him back into the apartment before he can manage to say how are you?

She wastes no time plastering her mouth to his, unbuttoning his shirt, herding him upstairs. It's passionate, almost crazy, like every Nikki Heat fantasy he's ever entertained.

Later that morning he studies Beckett, all business in her button-down shirt, and imagines her in a police cap with a matching short blue skirt, trapping him against the wall and shoving him onto his bed.

Kyra's lips are just as soft as he remembers and she's still using the same perfume.

"I wish I had gotten the hint and followed you," Castle whispers when they finally break apart.

Kyra rests her chin on his shoulder, touching her cheek to his. "I don't."

He pulls back and stares at her, stung. All these years, he's clung to the memory of the first and only woman who loved him when he was still poor and unknown, and now she's telling him that none of it was real? Voice trembling, he asks, "You mean you're glad we broke up? That you didn't love me?"

"Of course I loved you, silly," she laughs. "I'm just saying that when you lose one thing, you get something else. You and I would have been happy together. But then I wouldn't have met Greg, and we've been happy together too."

"That's true," he admits. "Greg's a lucky man. Me, not so much. I married wife number one for fun and found out she was an irresponsible cheating psycho. Then I fell in love with wife number two and ended up with ridiculous fights and an even more ridiculous divorce settlement. And in between, lots of shallow women who like money and getting to be in the newspaper."

"Come on," Kyra prods. "Isn't there anything good you would have missed out on?"

He thinks about Alexis—hearing her first words, holding her hand as she learned to walk, teaching her to cook, taking her dress shopping for the prom. Then he thinks of Beckett, uninterested in his wealth and unimpressed by his fame, unafraid to call him out for being a jerk, genuinely amused by his jokes and antics even though she tries not to show it, and his first true friend in a very, very long time.

"You're right," he tells Kyra. "I'm glad it worked out the way it did."

"I found a place," Beckett announces one morning, as she scrambles half a dozen eggs and he takes a whisk to the pancake batter.

He turns to look at her. As usual, she's wearing a loose fitting top but he can tell there's nothing underneath it. It takes all of his willpower to quell the physical reaction he has to this sight, to suppress the desire to run his hands under her shirt and carry her to bed.

"What's wrong?" she says, interrupting his train of thought. Her forehead is all scrunched up now, her green eyes concerned.

"Nothing. You found a place. I can't believe you managed to actually find an apartment with the housing market the way it is."

"It's just someone's extra room. It's the only thing I could afford."

"You could have stayed here as long as you like, you know," he says.

She looks distressed and evades his offers to help move. By noon she's out the door, suitcase in hand and blue coat draped over her shoulder. For the rest of the day, he has the same feeling that he'd experienced the time he'd gotten a cast removed and sensed something missing from his arm.

Alexis is in a rare foul mood, thanks to a combination of female hormones and something nasty Paige said to her during chemistry lab. She catches him staring absently at Beckett's favorite kitchen chair and she grumbles, "You don't have to stand around moping just because Detective Beckett is gone."

He decides that despite Alexis' intelligence, this idea is simply preposterous. Richard Castle has built a life around not getting attached to anyone, and he assures himself that he has no emotional investment in Kate Beckett, none at all. His dry spell over the six months or so has nothing to do with the fact that they've become good friends; he can still sleep with any woman he pleases without feeling guilty about what Beckett might think. So when Ellie Monroe phones him with one of the least subtle propositions he's ever heard, he quickly dismisses his first instinct to say no.

He has fun and he blames Beckett when the fun ends. But he doesn't mean it when he tells Ellie she can come back anytime; she's left him feeling dirty and uncomfortable. He tries to chalk it up to a natural reaction to being used, but he can't fight the nagging feeling that there's more to it than that.

The first time he falls in love with Gina, it happens on a book tour across the country. They spend all their nights talking in fancy hotel rooms and fancy bars and fancy hot tubs. The fights begin almost as soon as they return from their honeymoon. She yells at him for leaving the toilet seat up, for not calling her when he's running late, for going on father-daughter dates with Alexis without inviting her along. He yells back, blaming her for blowing things out of proportion. He doesn't realize any of it could be his fault until many years later, when Owen stands Alexis up at the movies, and she tearfully asks him why guys never say they're sorry.

The second time he falls in love with Gina, it's after Beckett and Demming have started getting serious. He tells himself it has nothing to do with the fact that he wants to kiss and nuzzle Beckett the same way that Demming's been doing. No, it's just that watching Beckett and Demming talking and laughing while making coffee, he remembers the long conversations and inside jokes that he and Gina used to have. So when she calls him about his overdue book and they end up spending three and a half hours chatting about the latest society gossip, he decides that inviting her to the Hamptons wouldn't be a bad idea at all.

Between parties and strolls on the beach, they rediscover their old passion. They continue to do fine when the summer ends. He still makes stupid relationship mistakes, but he makes fewer of them and he's better at apologizing to her. In turn, Gina's slower to anger and quicker to forgive than the first time around. Thanks to their newfound ability to compromise, they get along, but they don't really make a good team, and he realizes one morning that he's not in love with her.

She's not in love with him either. He sees it in the way she greets him with a cool peck on the cheek, stays completely silent when they watch movies together, and waits several days to see him when coming home from a trip with her friends.

Somehow they've both fooled themselves into thinking that they were in love—twice. He blames it on the expensive hotels, on his beach house in the Hamptons. (It reminds him of the time Alexis switched off The Bachelor in disgust, claiming that no one on that show ever really fell in love, that after a week in a lavish mansion even she'd be head-over-heels with David Carlson from economics class—definitely not a good thing.)

He's fairly certain that he and Gina can continue like this indefinitely, not quite happy but not quite unhappy either, channeling their frustration into petty fights but always making amends afterward. Some days he thinks it would be wise to settle for Gina. The older he gets the more he doesn't want to end up like his mother, past sixty and still jumping from man to man because she doesn't have the patience to stick around when the giddy infatuation phase is over.

Eventually he decides that the risk of winding up alone is worth the possibility of finding the magic Alexis had described—feeling something undefinable in his stomach and in his throat and maybe even in his ears.

Castle likes the way Beckett takes charge and works until she gets what she wants. He doesn't like it so much when her clone suddenly becomes pushy, especially when she decides that she wants him.

He starts telling her, "Natalie, I'm not interested in helping you with that kind of research," but he doesn't get a chance to finish because she's telling him to call her Nikki and shoving him against the wall of the elevator.

His body is starting to respond to the beautiful woman staring at him, so he just closes his eyes, rests his hands on her back, and enjoys the sensation of her tongue moving against his.

He frees himself from her embrace before they leave the elevator. She doesn't protest and she follows him at a respectful distance. Once they're standing on the sidewalk in front of the precinct, Natalie steps closer to him, takes his coat collar between her fingers, and with a toss of her hair says, "How about we take this back to my place?"

Logically, he has no reason to refuse; he's single again and Natalie's as gorgeous as she is willing. But looking at her, he gets an uneasy feeling, different from the delightful twist that hits his stomach when he sees Beckett at her desk every morning. The woman standing in front of him has the right clothes and hair and posture, but she's not Beckett; her perfume smells like gardenias instead of cherries, her bottom teeth are too crooked and her top teeth are too straight, her eyes aren't green enough, her breasts are too big (he never thought he'd have that particular complaint about a woman's body, but he has spent too long admiring the way Beckett's blouses and sweaters hug her smaller curves).

"I don't think this is a good idea," he stammers.

Not-Beckett looks equal parts incredulous and insulted. She lifts up her chin as if to challenge him. "Why not?" she whispers seductively, leaning in close enough that he can see his reflection in her eyes. "I could take all of your fantasies and make them real."

How could this be true, he thinks to himself, when lately all his fantasies have involved the woman who got a Lego stuck in her nose at age six, who loves con movies and comic books, who lost her mother but saved her father's life?

He stands up a little straighter and gives Natalie a firm "No." She presses her lips together and walks away without another word, her Beckett-boots clicking angrily.

That night in his dreams, Castle finds himself back in the elevator, holding Beckett in his arms.

He's kissed countless women before he met Beckett and he's kissed more women after he met Beckett, but he knows she's the last one he'll ever love.