Are we not formed, as notes of music are,
For one another, though dissimilar?
-Percy Bysshe Shelley

And so, after everyone had gathered up their things, Castle found himself walking along the sidewalk in the company of more than a dozen other performers, all chattering away. Castle tried to weave his way to Beckett's side, but the crowd and the conversation defeated him.

At the restaurant, where a large table had been reserved for them, he tried again to maneuver himself next to Beckett, but instead found himself wedged into a corner of the table between two chorus basses. Although their conversation was entertaining, he couldn't stop glancing over at Beckett, half the table away, engaged in her own conversation with some other orchestra members.

She still seemed calm, but more subdued than previously, and he wondered whether Howard's efforts to capitalize on her for publicity had rattled her more than she let on. Guilt sliced through him again, his brow furrowing with the worry that he had forced her into something she wasn't ready for ... but he remembered her saying You pushed just enough, and he reminded himself that she was an adult who could and did make her own decisions; so he told himself to let it go.

When the meal was over and everyone was milling around on the sidewalk outside, Castle managed to dodge through the crowd and get to Beckett at last. "Can I give you a ride home?" he asked quietly in her ear, and she startled slightly, looking up at him.

"Okay," she said, only a little hesitantly. So he just nodded and turned his attention to saying goodnight to the assembled musicians.

"Get some sleep, everyone," he advised cheerfully as he stepped over to the town car that was just pulling up to the curb. Beckett stood off to the side of the rapidly shrinking group, her arms folded, her lips pursed, shaking her head at him. But he detected a twinkle in her eye, so he opened the car door and leaned inside briefly to ask the driver to wait a moment.

When he straightened up again, Lanie was at Beckett's side, the two of them talking in low voices. Kate's head was bent down toward her shorter friend, her forehead creased, but one side of her mouth was curled upward in a half-smile. The others had all dispersed.

"Anything you'd like to share with the class, ladies?" he asked jovially, moving back across the sidewalk toward them. Lanie narrowed her eyes at him.

"Are you the teacher, or the class clown?" she asked, putting a hand on her hip.

"Ouch." Castle widened his eyes deliberately. "I'm sure I don't know what you mean."

"Uh-huh." Lanie turned back to Beckett. "Girl, we're gonna talk again, right?"

"Of course." Beckett exchanged air-kisses with her friend, and then Lanie sauntered off, throwing Castle a knowing smirk on her way by.

"Why do I get the feeling she knows something I don't?" he asked, holding the car door for Beckett.

"I don't think you really want me to answer that," she replied with a grin, pushing her violin case into the car and then sliding in after it.

Kate felt nervousness fluttering in her stomach again as she settled into the car and watched Castle climb in after her. This time, of course, it had nothing to do with singing or performing, and everything to do with the man sitting a couple of feet away, looking at her like ... well, she didn't even know what to compare it to, but the way he looked at her made her whole body flush hot and then cold, then hot again, and she felt very uncharacteristically tongue-tied. Like he's Frederic and you're Mabel, she remembered Lanie saying, and she remembered how she had scoffed, but now….

"That might have been the best cheeseburger I've ever had," Castle commented as the car pulled out into traffic. "I can't believe I never knew Remy's existed. You guys go there a lot?"

"Usually at least once or twice each concert week," she nodded, grateful for a neutral topic of conversation, "and like I said, we always go after the dress rehearsal. Just sort of a fun tradition."

"It was fun," he agreed, nodding. "Does Perlmutter ever join you? Or Howard?"

"No, never," she laughed. "They aren't really the types to socialize with the likes of us."

Castle was looking at her, assessing. "Howard seems remarkably lacking in tact for someone whose job is mostly PR," he commented slowly, his brows drawing downward.

Kate hesitated, knowing exactly what he meant. "Castle, don't worry about it," she said at last. "It's not a big deal."

His face cleared somewhat. "Well, as long as you're sure."

"I am," she nodded. It was true that Howard's efforts to publicize her role in the concert had taken her aback, but as she thought about it, she realized that she should have seen it coming. And there could be no way to avoid it; Johanna Beckett's daughter singing onstage was bound to be big news; she was making a spectacle of herself whether she intended it or not. She would just have to be okay with it.

"Okay," said Castle, unknowingly echoing her thoughts. He was quiet for a moment, and then commented, "I wrote a song about cheeseburgers once."

"Really?" she laughed. "I don't think I've heard that one."

"No, no, it never went anywhere - it's just gathering dust in some old notebook." He paused, looking thoughtful. "Maybe I'll find a way to work it into the new opera."

Kate's eyebrows went up as she remembered what Alexis had said last night about Castle's new opera. "Oh, the one you've been working on till all hours of the night? So," she said teasingly, "are you ever going to tell us what it's about?"

Castle's eyes focused abruptly, and a strange expression crept across his face. He looked embarrassed, and maybe a bit guilty. "Um," he said. He shifted in his seat and averted his eyes, and suspicion began to prickle at the back of Kate's neck.

"Castle," she said warningly.

He took a deep breath and looked back over at her. "Beckett ... the thing is..."

"Just tell me," she snapped, and once again he seemed powerless against the bite of her commanding tone.

"Okay," he sighed, "well, it's about this woman who is training to be a professional singer, but then her mother is murdered, so she becomes a cop instead. A homicide detective."

Kate felt her whole body go still, her jaw dropping open. A chill trickled down her spine.

"You're writing an opera about me?" she whispered unsteadily.

"Based on you," he corrected hesitantly. "I mean, none of the details are - I would never - it's just loosely based. But it's, you..." He stopped himself, took another careful breath, and said quietly, "You inspired me."

"Castle," she breathed, her heart pounding. She didn't know what to make of this at all. A whole opera based on her? What did he mean by you inspired me?

"Beckett," he said, sliding a little closer to her on the seat. He reached out as if to take her hand, but she pulled it away, staring at him, speechless. "Kate. Listen, until I met you, I hadn't composed anything for ages. Since the last Storm opera went into production."

"But that was more than a year ago," she said, blinking, trying to comprehend what he was saying.

"Yeah. And I had to force myself to finish it," he admitted. "I just ... lost my motivation, my inspiration. Nothing was flowing. I barely even touched the piano for months."

"What are you trying to say?" she demanded, feeling herself shrink back against the car's leather seat, trembling.

"The Storm series is done," he said in reply, meeting her eyes. "I'm done with it. It's gotten boring for me: the formulaic plot structures, the same musical motifs, the same characters. But then I met you, and suddenly I'm hearing all new music in my head." He winced and scrunched up his face in distaste. "Oh God, that sounds so trite and stupid, but it's true."

"Castle," she groaned, hoping like hell that he wasn't about to burst out with some ridiculous proclamation of undying love or something. But he shook his head firmly and leaned toward her to make eye contact again.

"No, Beckett, listen. You're ... extraordinary. You've had such pain in your life, but you work through it, and you're so good at what you do. And you don't take crap from anyone. I just - I just really admire that. And somehow, being around you has gotten me composing again. This new opera is going to be great, I can feel it."

"And it's based on me," she repeated, faintly. Kate was used to hearing histrionics - working with musicians and occasionally actors, one tended to encounter a lot of melodramatic personalities - but Castle's sincerity, his fervor, was captivating. Once again she found herself drawn in by him, all against her will.

"Well, it's a version of your story," he said carefully, "and like I said, all the details will be different. But you're the inspiration behind it, yeah." He tried a little smile and offered, "Every artist needs a muse, right?"

Kate sat up straighter at that. "Call me a muse again and I will break both your legs."

He grinned a little. "Okay."

She stared at him, her thoughts whirling.

"Your house, miss," the driver said, and Kate realized with surprise that the car was parked next to her building.

"Oh ... thank you."

"I'll walk you to the door," Castle said quickly, as she pulled her purse strap over her shoulder and picked up her violin.

"You don't have to do that, Castle."

"Oh, yes I do," he asserted firmly. "If my daughter finds out I didn't mind my manners, there'll be hell to pay."

"Well, we can't have you getting in trouble with your daughter," she murmured, unable to hold back a grin. She stepped out onto the sidewalk and Castle was at her side in a moment, the car idling at the curb.

"Are you mad?" he asked tentatively as they walked up the steps to her front door. She sighed, biting her lip.

"I don't know," she said honestly. She put her violin case down so she could dig into her purse for her keys. "I'm ... surprised. And I, it was a long day."

"That's for sure!" he agreed, his eyes widening. "We solved a murder today and everything. That was so cool."

"Oh, it was 'cool,'" she echoed, rolling her eyes, but she was grinning again, and Castle grinned back.

"Come on, it was."

"Okay," she conceded, huffing a little just for show, "maybe a little bit."

"Beckett," Castle said, and his voice was low again, and he was close to her again, the broad wall of his chest looming in her vision until she dragged her gaze up to meet his. She gasped and shivered a little at the heat in his eyes.

"What?" she whispered, her heartbeat pounding in her ears.

"What would happen if I kissed you right now?" he asked, so softly, and she smiled the tiniest bit at the words, remembering him saying the same thing a few hours ago.

Her knees felt weak, and she knew that she could step back - maybe she should - but her eyes were fixated on Castle's lips and she found herself murmuring, "There's one way to find out."

Castle leaned down slowly, his hand cupping her elbow, and she tilted her face up toward him, and his mouth met hers.

Heat flooded through her at the contact, and before she knew it her arms were coming up around his neck, the soft warm touch of his lips making her dizzy. She felt his hands sliding across her back to hold her closer, his tongue slipping out to tease at her lips. She moaned softly and opened for him, letting his tongue slide in and meet hers.

He pressed her back against the cold stone of the door frame, and she shivered a little more, tugging him closer. The hot weight of his body against hers was delicious. He kissed her as if he could learn her from the inside out, and she thought briefly that she might even let him.

But eventually he stopped, sighing, touching his lips to hers one last gentle time before pulling back. "I should..." he said hoarsely, and paused to clear his throat, "I should get home."

"Yeah," she agreed reluctantly, sifting her fingers through the soft hairs at the back of his neck one more time before pulling her arms back, though she left her hands resting on his chest.

"Kate..." he began, and trailed off, looking a bit lost.

"Don't stay up all night composing," she said with a little smirk. "Two concerts tomorrow."

"Right," he nodded. "I won't. And you should get your sleep too."

"Right." But she lifted up on her toes to kiss him again, her fingers curling around the lapels of his coat, and he sank into the kiss, his mouth moving sweetly over hers, lingering until they both had to stop for breath.

"Sweet dreams, Beckett," he murmured against her lips, and she smiled, reluctantly unclenching her fingers and pulling back.

"Goodnight, Castle."

He put his hands in his coat pockets and went down the stairs, and she picked up her violin and went inside.

Castle let himself into his loft in a daze, his brain buzzing.

He had sat almost completely still in the car, just soaking in the memory of Beckett's mouth, the long curves of her body pressed against him, and the many different timbres of her voice - the clear high soprano when she sang; the low sexy rasp just after he kissed her; and of course the many different tones and qualities of her speaking voice. He wondered if he would ever be able to capture all the voices of Beckett in his music, with only one lifetime allotted.

Moving on autopilot, he hung his coat in the closet, and then turned to find his daughter a few feet away, looking at him in some amusement.

"Earth to Dad?"

"Oh, hi, pumpkin," he said, trying to snap out of it. "How was your day?"

"Fine," she replied, coming over for a hug. "What about you? Did you catch a murderer and have a good rehearsal?"

"Yep, that sums it up," he agreed, moving toward the couch. "Gram's show is on, isn't it?" he added, looking at his watch. "You didn't want to go see it tonight?"

"I thought I'd see her tomorrow night, after your matinee," Alexis said, sitting down next to him. "Make a day of it. Maybe we can all have dinner in between, or coffee or something. Tea," she amended, because Martha Rodgers didn't believe in drinking coffee just before a performance.

"That sounds nice," Castle said, distracted again, this time by wondering what Beckett would be doing in between their two performances tomorrow.

"Dad? You're off in space somewhere," Alexis observed, looking at him curiously. "Do you need to go compose?"

"No, no. Can't get sucked into it tonight," he murmured. "Promised her I wouldn't stay up too late."

Alexis prudently didn't ask whom he meant by her; it was probably obvious, he realized. "I could come and shake you out of it, if you want," she offered. "It's not that late yet. You can compose for an hour or two."

"Maybe that would be a good idea," he conceded, and allowed his daughter to pull him to his feet.

But before he went to the piano, he took a detour into his study to look through his old notebooks full of half-formed and half-finished song ideas. After about ten minutes of digging, he managed to locate the one containing his cheeseburger song. He leaned against his desk, scanning the verses, softly humming the melody to himself. Alexis came in after a few minutes and steered him to the piano.

On Saturday morning, Kate slept late; she didn't get up until nearly 8:00. Instead of going for a run, she opted for some yoga in her living room, then showered and settled down with the morning newspaper.

Normally, it was her habit on concert mornings to eat a large, carb-heavy breakfast, to give herself energy and stamina for the long haul. But this morning she felt a little queasy at the thought, and she wanted to pamper her vocal cords, so she just ate a hard-boiled egg and a banana, and drank green tea with honey instead of coffee.

Just as she was finishing her food and the first section of the newspaper, her phone rang. She saw Lanie's name on the caller ID and picked it up.

"Morning, Lanie."

"Morning, Kate. Have you gone online yet?"

"Hmm? No," she said, wondering what her friend was getting at. "I'm just having breakfast. What's going on?"

"Well, just a heads-up, girl, the news about your singing this weekend is everywhere," Lanie said. "Howard's press release got picked up by the wires, and all the music blogs are exploding with it."

"Really?" Kate said a little faintly, her chest tightening with anxiety at the thought. Maybe she wasn't as ready to be thrust into the spotlight as she had thought.

"Haven't you seen the paper?" Lanie asked.

"I'm looking at it now. Why?" Kate said, flipping to the arts section as she spoke. "Oh."

Somehow Howard had managed to get the announcement onto the front page of the arts section - above the fold, no less, albeit in a narrow column on the edge of the page. CASTLE TO CONDUCT, BECKETT TO SING, read the headline, and the article quoted Howard's press release while adding its own breathless take on the news.

"Oh God," Kate muttered, flipping the paper over again so she didn't have to see it.

"Are you okay, honey?" Lanie asked. "I thought you should know."

"No, yeah, thanks for the warning," she sighed. "Yeah, I'm okay. I should have known this would happen."

"You could still back out?" Lanie offered, but Kate sucked in a sharp breath and shook her head firmly.

"No. No, that's not an option any more, Lanie." She paused, briefly biting her lip. "Not when I've worked so hard to get here."

"I hear ya." She could hear the smile in her friend's voice, the approval. It warmed her unexpectedly. "That man's really done a number on you, huh?" Lanie added, teasing. Kate felt one side of her mouth tugging upward against her will.

"I don't know what you mean," she teased back.

"Liar," her friend laughed. "So, you kiss him yet?"

Kate's cheeks heated up. "Maybe."

"That's my girl!" Then Lanie turned serious again. "He's good for you, Kate. Try not to fuck it up."

"Oh, gee, thanks for the vote of confidence." But she was smiling.

"See you in a few hours."

"Bye."

The phone continued to ring all morning, and Kate was grateful for Lanie's warning. She didn't answer it: not when it was old classmates or teachers from school, or former colleagues; not when it was reporters and editors, print and online and TV; not even when it was friends from the orchestra who happened to be sitting out this concert cycle. She let them all go to voicemail while she tried to focus on her pre-concert prep.

She spent some time practicing her violin, and some time doing breathing exercises. She did some vocalizations as warm-ups and sang some scales and arpeggios. She even tried to practice Rejoice Greatly a little bit, but felt too self-conscious and unfocused with the constant ring of the phone distracting her.

She was on the verge of deciding to unplug the damn thing when it rang again and she saw her father's name on the caller ID. For the first time since talking to Lanie, she answered it.

"Hi, Dad."

"Morning, Katie. You've been making quite a splash, haven't you?"

"Oh God. What have you heard?"

"Oh, nothing much," he chuckled, and she was relieved to hear the amusement in his voice. "Just a half-dozen calls already this morning, wondering if I knew what they've been saying about my daughter in the papers, the blogs, the discussion lists."

"I'm sorry, Dad," she sighed. "I probably should have warned you they were doing a press release."

"No, no, it's fine, baby," he assured her. "I can take it. I was used to this kind of thing, you know, back in the day."

Kate breathed, and breathed again. Together they took a moment to silently feel their shared grief.

"Not having second thoughts, are you, Katie?" Jim asked gently.

"No," she said definitively; but then, more cautiously, "Are you? About ... about coming to the concert?"

"No, God no, honey," he said immediately. "I said you should do it, and I meant it. I can't wait to hear you." He sighed slowly. "Katie, you were so bound and determined to blame yourself for ... what your mom did. So damn sure that it was all your fault. You gave up singing as a kind of self-imposed penance, and it didn't make you happy. It never has."

"Dad," she choked out, her eyes brimming.

"She wouldn't have wanted that," he went on softly. "Singing is a part of you, Katie, just like it was part of her. You need it."

"I needed her," Kate whispered, but she was thinking about Castle, and how he had said the same things. Singing is part of you. It's in your veins.

"Oh, baby." Jim sighed again. "I'll be there today, and I'll be proud of you. You're going to be great. I just know it." His tone lightened. "Now stop crying and blow your nose. You can't sing if you're all stuffed up and sniffling."

Kate smiled through the tears. "Okay. Thanks, Dad. I love you."

"Love you too, Katie."