A/N: I was overwhelmed by the amount of reviews on the previous chapter, and in less than a day no less! It really warms my heart, and thank you guys for such a warm welcome. This chapter is only a tad bit shorter than the previous one, but only because I wanted to break this single larger chapter in half.

A/N2: This one is still very angsty, and to be fair to you guys, I think it will stay that way for some time, because I really want to drag it out and emphasize what both Chuck and Sarah are feeling at this point. I promise it will all get to being happy and fluffy and Charah eventually.

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Sarah Walker was sitting on the edge of her bed, having driven to her hotel room after the encounter with Chuck. She could barely keep her eyes on the road, for Christ's sake! She felt like her entire existence was shrinking away. If only she wasn't so mute. She was mentally berating herself for not trying to explain herself better to the man she loved. Now she sat on her bed, her hands neatly clasped on her lap, staring at nothing in particular on the wall in front of her.

She felt cold, both physically and emotionally. Tears were no longer running down her cheeks; she'd run out of them - now her face was just frozen over. She tried to feel angry - after all, it was Chuck who had slept with that whore of an ex-girlfriend of his, not too long ago. She'd been crushed then, and could barely refrain from killing Jill Roberts - she more than once contemplated finding her and shooting her.

Now, even after they had gotten through that, Chuck springs it upon her that he wants to break up for the second time. She honestly didn't know how to react.

At this point, she was sure that Chuck Bartowski was the single most important thing in her life. She'd been sure of that for a while. As she sat there, thinking about that, she couldn't help but remember all the fun times they'd had. All the missions, the cover dates, the sleepovers, the evening games with his family. Even though it was punctuated by their awkward situation, and her constantly stopping his advances, she never felt like any of it had been a cover. She'd never felt so happy before.

She sighed in longing as she remembered the kiss in front of Roan Montgomery. Chuck had just suddenly taken control and kissed her with so much passion that she had never felt better in her whole life up to that point. For God's sake, claiming that she had to fix her lipstick, she'd had to run to the bathroom to get a change of underwear!

But it now seemed that she'd lost him for good. She couldn't cope with that. She knew that nearly everyone in Chuck Bartowski's life had previously betrayed him, destroying him and ruining him so much that he no longer believed in himself at all. She gasped knowing that that was probably how Chuck saw her now too! Someone who'd used him and discarded him, not caring about him at all, like so many before! If only he actually realised that he couldn't be further from the truth!

That started the tears up again. She contemplated this problem, because it was a problem. She had to get him back, she wouldn't stop at anything. She'd beg, she'd quit the CIA, she'd run away with him, she would do absolutely ANYTHING to get the life she wanted with him - one that she knew he also desperately wanted - or had wanted previously, at least. Her sobs shook her entire frame as she once again remembered Casey's words - that Chuck was finally shutting down. What did that even mean? She knew exactly what it meant. He was closing himself off, emotionally, physically. She couldn't let that happen!

God, she needed to stop acting like this. She was a grown adult, a deadly government agent, an assassin, and she was reduced to crying like a lovesick schoolgirl by a certain Nerd. She then remembered the text message that had so fatefully interrupted her talk with Chuck earlier - it had been Beckman, she had ordered the Team to assemble in Castle at 22:00 this evening. That was in about an hour. Probably some sort of mission.

She absolutely dreaded seeing Chuck right now, at least in her current state. Her hands were shaking. She'd get ready, and go.

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Sarah took a deep breath as she descended the stairs to Castle. The cold, sterile walls mirrored how she felt inside. She wasn't ready to face him yet, not after everything, but duty came first. The CIA demanded nothing less.

As she stepped into the briefing room, the soft hum of computers filled the air, a sound that had always felt familiar. Now, it only heightened the tension. There he was. Her lanky Nerd. Chuck was already there, sitting stiffly in one of the chairs, eyes fixed on the large monitor in front of him. He didn't even glance her way when she entered, but remained sitting upright, jaw relaxed, eyes staring uninterestedly at the screen.

"Agent Walker," he said flatly, his voice devoid of warmth.

Her heart sank at the formal greeting, but she didn't show it. Of course, he was hurt. She had expected that. What she hadn't expected was the chilling detachment in his tone. Not even "Sarah." Just Agent Walker. She swallowed the lump in her throat and took a seat across from him, hoping the pain didn't show on her face.

Casey, leaning against the back wall, grunted in greeting, arms crossed as he waited for the briefing to begin. He glanced between Chuck and Sarah, sensing the palpable tension. He secretly hoped they wouldn't do something stupid and slip up in front of the General.

The large screen flickered to life, revealing General Beckman's stern face. As usual, she didn't waste any time with pleasantries.

"Team, we have a situation that requires immediate action. We've received intel that suggests there is a FULCRUM cell operating from the villa of a rich businessman named Christopher Hawkins," she stated, her voice slightly garbled by the cable connection. She glanced at each person in the room individually. "We believe the cell could potentially compromise national security." She eyed Chuck. "Mr Bartowski and Agent Walker will pose as a loving couple, and will use this cover to access the offices within the Hawkins villa, where we believe the hard drive containing encrypted FULCRUM data to be. I want it destroyed at all costs. Is that clear?"

"Understood, ma'am," said Casey.

"Understood, General," Chuck nodded stiffly.

The way he spoke—it was as if he was on autopilot. The passion, the warmth, all of it had been drained from him, leaving only a soldier doing his job. Sarah's heart ached at the sight, but she had to focus.

"Is something wrong Agent Walker?" Beckman asked, leaning towards the camera and frowning at Sarah as if she had grown a second head.

"No, General. We'll be ready," replied Sarah, finally getting a grip on her exterior looks and schooling her features and her voice.

"Very well," said Beckman, and broke the connection with her usual abruptness.

While the General had been talking, Chuck was staring stoically at the screen, his posture rigid - something that was very uncharacteristic of him. Sarah had secretly tried to steal a few glances at him during the short briefing, searching for any sign of the man she so loved, but all she saw was a wall - a barrier he'd put up to keep her out.

For a moment, there was only silence. Casey pushed off the wall, moving toward the equipment rack without a word, but Sarah remained frozen. She wanted to say something - anything - to Chuck, but the words wouldn't come. The sharp pain of his indifference kept her silent.

Chuck stood, moving toward the door without looking at her. "I'll check the gear," he said to no one in particular, his voice still devoid of the warmth she had once relied on.

Before he could leave, Sarah's voice finally broke through the silence, soft and pleading. "Chuck"

He stopped but didn't turn around. His back was to her, his shoulders tense. "Is there something you need, Agent Walker?"

The formality of it hit her like a punch to the gut. Agent Walker. Not Sarah. Never Sarah anymore. She blinked back the tears that threatened to spill, knowing that in this moment, there was no room for weakness.

"No," she whispered, her voice barely audible. "Nothing."

Chuck left without another word.

Sarah sat there for a moment longer, staring at the now-empty space where he had stood. She could still feel the coldness in the air, the distance that had grown between them - distance that felt insurmountable.

Casey, who had been watching the exchange from the corner of the room, finally spoke, his tone gruff but not unkind. "You'd better fix this, Walker. We can't afford to have Bartowski going cold on us in the middle of a mission."

Sarah wiped at her eyes, steeling herself as she stood. "I know," she said softly. "But I don't know how."

Casey grunted, adjusting his gun holster. "Figure it out. Fast."

Sarah nodded, her resolve hardening. She would. Somehow, she would find a way to break through the walls Chuck had built around himself, just like he had many times done to her.

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Chuck was far enough away from the main room of Castle to not hear what was being said. He didn't care, really. He didn't care about anything much anymore. Without Sarah, life just wasn't that worth living anymore. However, he knew he had to keep going, if only to keep whatever shred of normality there was left in his life.

He bent over the small table with the gear for the mission spread across it. He went through the communication devices, the earpieces, the bullet-proof kevlar vests methodically. Because he couldn't think of anything else to do. Today, it felt like a part of him, a vital part of him that made him who he was, made him happy and caring and Chuck - had shrivelled up and died. As if it was poisoned from the inside.

Sarah didn't care about him. Not outside of the job, anyway. Her job was to protect the Intersect. That's all it had ever been. Well, he'd make damn well sure that he never made the same mistakes again. He stood there, checking the equipment over and over, his face blank.

Although he knew he had the option of doing so, he knew in his mind that he wouldn't ask for Sarah to be reassigned, not because he cared or hurt, but precisely because he didn't care. Their relationship was going to be strictly professional.

'Is this how spies feel?' he asked himself as he realised just how shut-down he was. He could recognize his mind was near its breaking point, near Snapping. But he didn't care. All he cared about just now was completing this mission successfully, because it would make him think less about what happened.

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A/N3: See you guys again soon :)