A/N I didn't really plan on doing a best-friend challenge, but the idea seemed to resonate with a lot of those who left comments, so I'll see what I can come up with.

"Anyone you like."

"He called me Sam."

"Let's get to work."

"I have to challenge you, Sarah Walker."

At the Orange-Orange…

She heard the back door of the freezer crack open, even as the front door bell marked Morgan's departure. The register had a monitor for the stairs, just as the stairs had a monitor for the store. So she wasn't taken by surprise when she heard Chuck's voice. "What was he here for?"

Sarah inspected her bracelet closely. "He wanted to know about Sam."

Chuck smiled, safely hidden from view by anyone but her, and she wasn't looking at him. "Well, he should have come to me, I know all about her."

"As much as anyone does," said Sarah to his profile on her monitor. "More than me, even, and what little I do know is Chuck-classified." By Chuck, for Chuck, because of Chuck. "Morgan got very upset when I wouldn't tell him anything."

Chuck lost the smile. "Oh, no…"

"He challenged me to a duel."

"Are you sure you wouldn't rather come on the mission?" asked Chuck, sounding concerned. "You might get lucky and meet the Ring assassin first."

Sarah laughed. "So I can either steal Jones' moment of glory in order to play newlywed with Shaw, or I can stay and fight for what's mine." She put a finger on her chin and gazed up at the ceiling. "Hm, let me think."

Chuck tried again. "He's very determined."

"So am I," said Sarah. "And I have resources he doesn't have." She stroked the register, and by extension, Castle, and by extension, everything she knew and had done in her entire spy career. "Maybe you could–"

Chuck took a step back, flashing a quick look at the monitor there. "Ohhh!"

Sarah recognized the exaggerated cry of distress, but knew it had nothing to do with cheese. They didn't do cheese, although with the success of the guac maybe they should. "What?"

"Too late. Everybody's ready, have to go, love you, 'bye." Chuck ducked back into the freezer.

Sarah sat on her stool, staring at her bracelet. Love you. 'Bye. The story of her life, except for the 'love you' part. That was new, that was…nice. 'Love you' plus 'bye' equaled 'going away, and coming back'. Something to look forward to, that coming back.

She looked forward, into the lot, and world outside, and the Buy More, part of that world. And Morgan, part of the Buy More. Mission-critical resources came on-line, and she sat up, no longer tired. "Challenge accepted," said the Ice Queen. She flipped on the sonics.

Down in Castle…

Sarah's phone rang. "Chuck? Is something wrong?" He shouldn't be calling her on an op.

"No," said Chuck. "Mr. and Mrs. Beautiful Couple are just checking in, and Casey's off playing telephone repairman. I'm beginning to see why he grumps about being stuck in the van all the time. Do you have any idea what a small percentage of my awareness I'm using right now?"

"Next time bring a comic book."

"Graphic novels, please, and they're too much work. You're a much bigger bang for a much smaller buck, plus you won't mind if I have to hang up on you suddenly."

"Oh, I'd mind," said Sarah, aware of just how much it would bother her if he suddenly dropped off the network. That had happened too often in the past for her to not know, but this time he was in the van, safe as houses. "I'd just understand."

"That's my girl."

"Your girl, huh?"

"Yes, but in a semi-sort of-craftsman-y way, not possession," said Chuck. "My girl, my real girl, as opposed to my kickass ninja spy handler. That one wouldn't mind, she'd just react."

True. Wait. She looked up at the monitor.

"So what are you up to, real girl?"

"Spying," said Sarah brightly. "On Morgan."

"That's cheating."

"Told you," said Sarah. "All's fair in…in…" She puffed into the microphone. "Dammit."

"I am both understanding and patient," said Chuck. "So what's Morgan up to?"

"Nothing," said Sarah, grateful for the change of topic. He'd probably planned it that way, or something. "He and the Wonder Twins are listening in on Big Mike's office."

"No more Saturday cartoons for you."

Suddenly the screen showed a frenzy of activity. Lester started doing pushups, but she wasn't sure what the others were supposed to be doing. "What the hell?"

"What?"

"If they were up against competent adversaries, they'd have been so busted, but fortunately this is the Buy More," said Sarah. "Big Mike caught them red-handed, but he was talking to a bunch of suits and didn't notice. These guys are trying to buy the store."

Chuck paused a moment before responding. "Do we believe that?"

"No, we do not," said Sarah, tasking the monitors to follow the new guys. "It's barely worth the effort, thanks to Morgan and Casey, but you can bet the CIA has ears out for any such acquisition plans. You should have been telling me. Us. Them. Their inspection team just came in the door."

"That's fast."

"Too fast, if you ask me," said Sarah, trying to keep up with all the moving targets at once, using a much larger percentage of her awareness. "I have to go."

"So do I. We're all checked in, time to start scanning. Keep me in the loop."

"Will do."

Sarah hung up, putting her suddenly-freed-up brain power to work making a report for the General, including head shots. Then she made the mistake of looking up. Morgan was heading out the door. "Uh-oh." She hit the send button and ran upstairs, killing the sonics as she settled into her seat.

A few seconds later, about as long as it took a short, agitated man to cross a parking lot, a short agitated Morgan walked into her store. "Challenge number one," he said loudly. "Will Chuck take your call at any time, day or night?"

He'd better not. She wondered if Morgan had already tried. Points for courage if he had. She picked up her phone and showed him Chuck's smiling face as she pressed the button. The phone rang, but no Chuck. "Apparently not," she said, trying to sound annoyed.

Morgan leaned on the counter. "Me neither," he said, "So that's a tie. Keep trying, though."

"Why?" asked Sarah.

"Some guys in the Buy More, thinking about buying. Chuck has to get back here, even if he is mostly independent. They're interviewing the whole staff. Lester's in there right now."

"You know, Morgan, I hate to say this, best-friend challenge and all, but you really are a good friend," said Sarah, "All the way over here, while Lester's over there, probably spilling his guts."

Morgan raised his head, eyes wide, suddenly aware that he didn't have a Stanford degree. "Crap, you're right." He ran out the door.

Sarah dialed up the sonics. "Back to work."

Meanwhile, in the back of the van…

Chuck listened in on the Ring agent's call as the tracer did its job. "He's in conference room two, you can't miss him. He's the one with the hair." There we go, room 4305. He passed the info to Casey. Then he pulled up the schematics of the hotel so his partners could saunter casually past conference room two without having to ask where it was.

'The one with the hair'? What was going on in conference room two?

Down in Castle…

"Where is the rest of your team, Agent Walker?" asked Beckman.

"Jones was on duty when a Ring agent came into the store and bought our most popular flavor."

"The guac?" asked Beckman, with a shudder. "Jones fell for it?"

"Yes," said Sarah, "Although, given her experience level, it wasn't a bad pickup. Chuck identified him and Shaw decided to follow up."

Beckman sniffed. "Well, at least he had the good sense to leave you in place. You're quite correct, Agent Walker. There are no plans in motion to acquire the Buy More by any legitimate interests. We would have quashed them if there were. Agent Shaw, it seems, has a taste for herring."

Devon shifted uncomfortably in his seat when his phone buzzed with an incoming message. Go to the men's room. Chuck. He shifted over to whisper in Ellie's ear. "All this talk of urinary tract infections has given my bladder ideas. Hold my place?"

"Against all comers," said Ellie with a yawn.

Once free of the meeting, Devon looked for the nearest bathroom. As he washed his hands Chuck came out of a stall. "What are you doing here, Chuck?"

Chuck held up a picture of the guac-buying Ring agent. "Have you seen this man today, Devon?"

"Yeah, we were on line and he tripped over a plant. I helped him up."

A line full of doctors at a medical convention. Chuck nodded, and raised his watch to his mouth. "Not Devon, guys. Just the first helpful person he came across. This smells like a setup to me."

Devon looked concerned. "Chuck, what's going–?"

Chuck raised a hand as he was listening to two people talk at once. "Aborting." He looked at Devon. "Enjoy your conference." He headed for the door.

"Are we in danger?"

"Nope," said Chuck. "Just…wrong place, wrong time."

Devon wiped his hands dry. "You got that right."

Sarah walked into the Buy More, holding a bag. She looked around, and saw just about everyone clustered over by the cash registers, so she sauntered casually over. "Hey guys," she said, "You didn't come over like usual today." She lifted the bag. "Brought your favorite."

Jeff took the bag, as Lester exclaimed, "We're doomed."

"Yes, but it's a green doom," said Jeff, handing out spoons.

"That's as good a name for it as any," said Sarah. "Why are you doomed?"

"The boys lived up to their reputations," said Big Mike. He pointed to yet another parabolic microphone, with a recorder built in. Lester hit play.

"Grimes said this guy Chuck is his best friend, and it's clearly this 'Chuck' that we want. We can use both of them to our advantage," said one voice.

"What do you want me to do about the others?" asked a second, deeper voice.

"I think we need to be conservative here," said the first. "Terminate the rest."

"I just got this job back," said Big Mike, practically in tears. He didn't know the danger he was in, and Sarah couldn't tell him. "They haven't even seen Chuck, but they're keeping him." He shook his head in wonder. "I wish I had a friend like Morgan."

"We should have been nicer to the gnome," agreed Jeff sadly.

Sarah looked around. "Where is Morgan?" She left the others to their lamentations and yogurt, moving into the empty store. Morgan's 'office' was a former broom closet somewhere down this–

"Sarah?" said Morgan, jumping out at her.

"Morgan?" she said. "The others are all looking for you. They've got good–"

Morgan surprised her by putting a hand over her mouth, so surprised that she didn't reflexively break it in three places. "Me first," he said. "What you got is nothing compared to what I got."

Suddenly realizing where his hand was, he took it away. "There is a secret underground CIA base under the Buy More."

Sarah let him babble about 'bad guys', marveling at the timing. If she hadn't left Castle, or the Double O for that matter, on her little recon mission, she could have captured these guys as they went in. Or perhaps they would have captured her. The scanner in the lockers had always been the weakest point in their defenses, too visible to have real security built into it.

She had to get back to the store, right now. She should be able to gas the place, if they didn't kill all the internal security systems first. "Um, I have to go…" she said, pointing a finger in some direction.

"I know," said Morgan. "You're thinking this is some lame 'Best friend challenge' stunt, but it's not." He grabbed Sarah's wrist before she could pull further away. "I'll prove it to you."

A/N2 I hope you'll drop me a line and tell me what you think of this rewrite so far.