I don't write much fan fic, and have never before done one in immediate response to an episode. But this idea just jumped out at me after Setup.

Usual disclaimers apply.

Remember:

It was finally over. The apparently straight forward cabbie killed in the course of a robbery that became a desperate race against time to stop another terrorist attack on the City. Another one. That's what Castle couldn't get out of his head. He'd kept thinking of that day, nearly 10 years ago now. Trying to comfort a scared and confused 8 year old when he himself could barely comprehend what had happened. The eerily deserted streets, at once quieter than usual but noisy with the constant wails of sirens. The smoke and dust and smell.

Looking around the squad room at the weary men and women slowly gathering their things and leaving the building he knew they'd all been similarly affected. His gaze drifted to his partner as she came out of the Captain's office, the toll the last few days had taken obvious in her bearing.

He didn't even think about it, just grabbed her purse and jacket, intercepting her before she could reach her desk. He knew he'd been right when she didn't protest as he ushered her into the elevator, out of the Precinct and into the cab he hailed. She looked ready to fall asleep during the ride but roused when the cab pulled up in front of her building, remembering to stop in the lobby to collect her mail, even holding her door open for him after unlocking it.

Kate headed upstairs and soon Rick could hear water running. He dropped his coat on a chair, rifled through the stack of takeout menus until he found the one he wanted and called in an order. He was just opening a bottle of wine when Kate, in sweats and slippers, her damp hair pulled back in a pony tail, came down.

"That was fast." He poured two glasses of wine, handing her one as they sat together on the couch.

"Lots of practice with all the call outs at odd hours."

"I called in for Chinese. Hope that's OK." She nodded.

They sat, sipping their wine, not talking. After a while Castle broke the silence. "I've been thinking about that day a lot during this case. I imagine we all have been. And I realized we've never talked about it."

Kate thought for a minute. "You're right and that's odd, don't you think? That's one of those things that usually comes up when New Yorkers, everyone from the Tri-State area really, get to know one another."

She drank a bit of wine, then plunged in. "I didn't lose anyone close to me, though I did know a couple of the First Responders. A friend from college had just gotten off the PATH when it happened. She was later than usual that day because it was her birthday. May have saved her life. What about you?"

"No one I knew was killed, luckily. My broker at the time worked in one of the Towers but their offices were on low floors so they all got out. My building got a coat of dust and the smoke smell got into everything."

"I never thought of it, how close you would have been. Did you actually see them fall?"

"No. I'd just come back from dropping Alexis at school, stopped to vote. I heard this loud boom while I was in the booth, saw the fire when I came outside. That's about when the second plane hit, which I did see." Castle closed his eyes for a moment, remembering. "I didn't stick around, just went back to the school, pulled Alexis out and took her home. And tried, not too successfully, to calm her and answer her questions - What happened? How? Why would anyone would do something like that? As soon as they reopened the Brooklyn Bridge I took Alexis out to the Hamptons, stayed there until Sunday.

What about you? You were a cop already, weren't you?"

Kate nodded. "I'd been on the Job just over a year, still in uniform. I was one of the cops who were kept on normal patrols, as much as anything that week could be considered normal. There was some concern that there'd be the kind of problems we get during a blackout, looting, arson. There was very little of that, as it turned out. But there was this one situation in my patrol area, actually helped me make detective pretty quickly as it turned out."

"Do tell."

"There'd been some push-in home invasions, maybe four or five over two months. Retirees coming home, same two buildings, buzzers but no doormen, always tenants on the first of second floor. The perp got ambitions, hit 2 more apartments Tuesday, then again Wednesday morning. A friend of Nona Maria."

"You had an Italian Grandmother?" Castle punctuated his question with a raised eyebrow.

"What if I did?" Kate challenged, but explained anyway. "But no, Chris, my best friend all the way through middle school, Nona Maria's her grandmother. Chris went there most days after school, and I went with her. Perfect arrangement, since both our parents had full time jobs. Nona's the one who taught me how to eat a whole artichoke, and snails, and introduced me to all sorts of vegetables I'd never hear of. She and my mom exchanged recipes all the time, the kinds where you have to watch the person cooking so you know how much a pinch of this or a little of that really is." Kate smiled, remembering the days she and her mother spent concocting good things to eat. She really needed to start cooking again.

"Anyway, Wednesday morning I respond to a robbery in progress, alone because we were stretched so thin, to discover that Nona was the one who called it in. One of her friends was the victim. And the guy'd gotten rough that time, woman broke her arm he pushed her so hard. You have to remember, I'd spent almost every afternoon there for years, knew the neighborhood. Something jumped out at me that the cops who caught the earlier calls wouldn't have realized. A hot dog cart."

"Wait a minute. A hot dog cart? They're on practically every corner."

"Not this one. No office buildings, not a street many commuters or tourists use, there just wasn't enough food traffic to make a go of it. Every once in a while someone would set up but leave again after a couple of weeks. This one had been there every day since just before the robberies started."

Rick caught on "Hiding in plain sight. Food carts are so ubiquitous no one really notices them."

"Right. I hadn't at first, but Nona mentioned it when I asked if there was anything that seemed different. Soon as she said that it clicked. We came up with an impromptu sting operation. I made sure he noticed me leaving the building, calling in my location and status when I hit the sidewalk. Then doubled around to the service entrance, where the super was waiting. Mrs. Lord, one of Nona's neighbors, was about as tall as me, similar build and coloring. I borrowed some of her clothes and her purse and keys, pulled my hair up in the same sort of bun she wore, a little make-up, a bit of a slump, and from a distance I passed as Margaret."

"Oh, I have got to use that for Nikki. Maybe with a grey wig and cane?"

"Castle!" The chiding was more amused than annoyed. It did make a good story. "So, after lunch Nona and I headed out, talking about how we wanted to get money out of the bank 'just in case'. She found a couple of old teller's envelopes, stuffed some ripped newspaper inside to make them look full. When we came back to the apartment I 'inadvertently' pulled one out of my purse when hunting for my keys. The fake hot dog guy stopped the door just before it closed, not open enough for anyone to notice unless they were looking for it, which I was but not so he realized. When he heard the elevator he came in, saw it stopped on, two then ran up the stairs. Fit, young guy, easy to run up a flight of stairs, come up behind an older woman before she could unlock both locks."

"But instead of a retiree he got a 22 year old cop."

"Exactly. You should have seen his face when I dropped him. It was the one bright spot that week, stopping a lowlife who preyed on the elderly. Then it was back to 12 hour shifts, responding to frantic calls about suspicious packages that turned out to be someone's trash or suspect activity that was just kids hanging out, all accompanied by the constant dire news. When things returned to normal, or rather what's passed for normal since that day, I got called into the Captain's office. After the obligatory chiding for involving a civilian he complimented my initiative and transferred me over to plain clothes, where I could 'make better use of my acting skills'. Gave me an edge when a detective slot opened up."

"So, silver lining, if you'll pardon a cliché."

The food came then. Castle paid the delivery kid, and they settled in to eat and swap stories, until the last couple of days finally caught up with them and Castle left, yawning, just before midnight.