Disclaimer: I do not own NCIS or Castle. But asdjhfjflsakjdfsjf I wish I owned the Castle finale! INCREDIBLE.

A/N: So I guess this falls into the mould we've seen of people telling Beckett to stop being a bloody idiot. Most notably, Royce's letter *sigh at wonderfulness*. But yeah, it's a crossover set in Season 1 of Castle, and Season 5 of NCIS. Montgomery has forced Beckett to take leave, and she's going on holiday down in Florida, stopping off to see her old friend Jenny Shepard in D.C. for one night. I know the timelines don't quite work out, but just... give me a little rope, mmkay? Hopefully not enough to hang myself with.

A/N2: FIRST CROSSOVER EVER. Excited to check the little crossover box, ngl :P.

A/N3: There may or may not be a little bit of David Boreanaz fangirling thrown randomly into this otherwise very serious fic. It's for Tiva4evaxxx, FadeIntoTheBackground, and OzBabe, because I love them, and they love him. A. Lot.

Jenny was just finishing in the kitchen when her doorbell rang. She ran through to open it, smiling widely at the sight of a young woman she hadn't seen for far too long.

"Kate! Come in, I'm just finishing dinner. I was going to take you out, but I thought you might prefer something more relaxed after your flight."

"You thought right," groaned Kate Beckett, dragging her suitcase through the door. "It was hell. I'd rather spend ten hours in a locked room with Castle."

Jenny laughed. "Leave your bag at the bottom of the stairs. And yes, I heard about the new man in your life."

"It seems like everyone's heard about my new 'consultant'," Beckett replied, with a heavy sarcastic emphasis on the last word.

"Consultant," repeated Jenny, pouring two glasses of wine with a smirk. "Is that what they're calling it these days?"

Beckett's jaw dropped in indignation. "You can't be serious. You don't honestly think I'm another notch on Richard Castle's bedpost, do you?"

She shrugged, amused. "Perhaps. Maybe more than that? Just because a man has a reputation doesn't have to mean he fulfills it."

It looked like Beckett was considering this as Jenny served dinner and they sat down at the table, however if Jenny knew her friend, it was more likely that she was taking the time to formulate a response that would shut Jenny up. But not tonight. She was on a mission to help Kate, whether the woman liked it or not. She didn't have much time left to help anyone, after all.

"I'm not avoiding him because of his reputation. Not really, anyway."

"So you don't find him attractive?" Jenny asked, in a tone that showed full well that she knew better.

Beckett paused. "Well, I love his books, you know that." When Jenny was still expectantly silent, she reluctantly added, "And I suppose he does have a sort of charm."

"So what's the problem?"

Despite herself, Beckett laughed. "It's not that simple."

"It should be," Jenny said, no longer joking. "You're interested, he's interested from what I've heard."

"And read in gossip magazines," Beckett interjected, but Jenny ignored her.

"I think the human race overcomplicates the most simple things."

"How philasophical," she commented, a note of worry creeping into her voice. "Are you okay, Jenny?" Something told her that Jenny's musing wasn't entirely joking.

Jenny swallowed and forced a smile that didn't reach her eyes. A combination of the wine and the presence of a friend completely removed from NCIS, not to mention the burning secret that had been building up inside her for months with no outlet led to the honestly that followed.

"I'm dying, Kate," she said. "Which is why I was so happy you said you were coming by. Not that it isn't always a pleasure to see you."

For Beckett, cliched though it may have been, time froze. The silence stretched for miles between them.

"How long?" she choked. "How long do you have?"

Jenny saw the pain in her young friend's eyes and was reminded of one of the many reasons she hadn't told other people. She never wanted to have to hurt her friends like this.

"A few months longer," she answered, trying to be the calm one but internally struck for the thousandth time by just how short it was.

"How long have you known?" Bekett asked, her voice steady now, but lower and quieter.

"Longer than I have left to live," Jenny replied.

"Why didn't you call me?"

Jenny ate a mouthful of her dinner, mostly to prolong answering, since the medication had long since robbed her of any real appetite.

"I wasn't going to tell you," she eventually said, looking down so she wouldn't have to see Kate's eyes shining with unfallen tears. "I wasn't going to tell anyone. In fact, I haven't told anyone else except Ducky, who did my blood tests for me, and I swore him to secrecy. Thank god for doctor-patient confidentiality."

Beckett frowned, a furrow appearing in the middle of her forehead. "You idiot," she said softly. "Why not? You have friends who love you and want to support you, through everything, even through this. So you what, decide to just go through it all on your own? What about Gibbs?"

She dragged up the name that had been present in so many of her conversations with Jenny over the years, every small detail giving her a patchworked idea of what had really happened in Europe – and what infuriatingly hadn't happened since they met again. She knew that there was still love there, although Jenny had never said it in as many words.

"Gibbs and I haven't been close for a long time," Jenny said, trying and failing to keep the hints of sorrow from her voice. "It wouldn't be fair to expect him to be by my side, just because we were intimate once."

"You weren't intimate," said Beckett scornfully, "you were in love."

"And I wrecked it," Jenny interrupted before she could continue. "I wrecked it years ago. Which is what I wanted to talk to you about, because you're pretty damn close to making my two biggest mistakes."

"I don't understand."

"Revenge isn't worth anything," began Jenny, somewhat cryptically, and it seemed to Beckett that she had completely changed conversation. "Take it from me, I should know. I got my revenge, Kate. The revenge I'd been seeking for years, like you've been seeking yours. And you know something? All those people along the way, who tell you that it isn't worth it, that you should move on? The ones you hate, the ones you protest to yourself just don't understand?"

Subconsciously Beckett was nodding, silent. She'd had her suspicions about what had happened with La Grenouille, but she far from knew the whole story, and Jenny had never confirmed anything before.

"Well it turned out that they knew best all along. It really doesn't help anything at all. It's satisfying, for a few seconds. But is a few seconds of satisfaction really what you want out of your whole life? I thought it would be enough for me, and I was wrong."

"I'm not giving up," Beckett said firmly. "You might be right, you probably are, but I have to know for sure. I have to find them."

Jenny smiled a sad smile and carried their now empty plates off the table, dumping them into the sink to deal with later.

"Yes, I thought so, but I had to try. Which brings me to my second point, my second mistake. Don't run away from loving someone. It seems smart but it just hurts like hell."

"I don't love Castle," Beckett said immediately.

"Maybe not yet, but you're trying very hard not to love him," Jenny replied, choosing not to point out that whenever Beckett said his name, her face lit up like that of a woman in the process of falling head over heels. She'd work it out. Jenny just hoped she'd have the guts to go for it.

"Jenny, I'm really sorry that -"

"You're really sorry that I'm dying, don't worry, I know you are. But I'm not some mad terminally ill woman trying to project all her faults onto the young and healthy."

"I didn't say you were."

Jenny laughed. "You were getting there. Obviously you would have been more polite about it."

Beckett looked stubborn for a moment, thinking about arguing, then laughed with her. "Fine, I was thinking about it."

"With everything I've done in my whole life, and the many mistakes I've made, those are the only two I'll die really regretting. I'm too late, but I don't want you to make the same mistakes. Just think about it."

"I doubt I'll be able to think about much else now."

"I'm sure I can distract you," Jenny grinned, glad to have said what she wanted to say, but now desperate to move on. "I was thinking we should have a David Boreanaz marathon. I have Bones and Buffy, where do you want to start?"

...

By the time they woke the next morning after an unwisely late night, Beckett didn't have long until she had to leave to get to the airport in time for her flight to Florida, her final destination for the leave that Montgomery was forcing her to take. They ate a hurried breakfast and she called a cab.

"It was great to see you, Kate," Jenny said as they stood at the door. "Sorry about everything."

The statement was completely vague but Beckett understood.

"Don't worry about me," she said, shaking her head. "I only wish you'd told me sooner. You should tell Gibbs."

"I can't," Jenny admitted. "I've tried."

"Write him a letter then," said Beckett, knowing that arguments would be futile. "It's going to hurt him, and you should explain."

"And you should make a move on Castle," Jenny retorted, determined to give her point one final push.

"Shut up."

"He might not wait around forever."

"Okay, my cab's here, I don't need to put up with your nagging, I'm leaving now."

The women laughed and embraced one last time before they separated for what would be the last time, and Beckett walked out the door, waving back at Jenny with a warm smile and a heavy heart.

Kate had only been there one night, but the house felt empty now she was gone again. Thinking about her parting advice, Jenny sat down at her desk and pulled the lid off a pen, laying out a sheet of paper.

Dear Jethro,

she wrote.

Sitting in the back of the cab, Kate pulled out her phone, which she'd been ignoring while she was with Jenny. There was one message from Castle.

"Glad the first flight arrived safe, shame about the crying baby though. And don't lie, you'd love to spend ten hours alone in a locked room with me ;). Have fun with your friend. xxx"

She laughed, forgetting that she'd shared that with him as well as Jenny. Her laughter was cut short at the thought of her dying friend, she was still reeling from the revelation, and the wisdom that Jenny had seen it as her place to give. And who knew, maybe she was right.

"Castle, we should talk when I get back to NY," she began to text, then erased it. Eventually she replied "You wish, Castle. Had a great time thanks, will text when I get to Florida. Having fun at the precint without me? Xx".

Jenny Shepard looked at the opening of her letter as Kate Beckett stared at a blank text message, both trying to find the right words. In the end, almost simultaneously, they sighed and gave up, thinking the same thing.

I'll get around to it.

Later.

So to me this seems a bit OOC for them both. I've never written Beckett before, I have no excuse about Jenny. But I loved the idea, so I just ran with it. Hope you enjoyed :).