Chapter One — A Tense Reunion !

Seattle Grace was never quiet. Not even in the early hours of the morning. The hospital thrummed with its own pulse, a relentless rhythm of life and loss, emergencies and solutions. Nurses moved briskly down the hallways, their hurried footsteps blending with the hum of ventilators and the shrill cries of pagers. The air was sharp with antiseptic and a faint bitterness of overbrewed coffee, and even the quietest corners seemed alive with the faint buzz of fluorescent lights.

Nate Mercer stood in the middle of the hospital lobby, his figure a picture of calm amidst the chaos. He wore a tailored navy coat over his scrubs, every line of his posture meticulously composed, his polished appearance out of place among the whirlwind of scuffed shoes, messy ponytails, and hastily buttoned lab coats.

And yet, Nate looked as though he belonged anywhere. He had that kind of presence; poised, confident, unflinching. But there was a shadow in his eyes, something deeper and more fragile that betrayed the weariness he carried like a second skin.

He glanced at the bustling scene around him, not out of discomfort but out of habit. His gaze was sharp, analytical, taking in the space like it was a puzzle to be solved.

"Dr. Mercer."

The voice was steady and warm, a mixture of authority and welcome that cut through the noise like a scalpel. Nate turned and found himself face to face with Richard Webber, the Chief of Surgery.

Webber was an imposing figure, his presence commanding the room even in his simple white coat. His expression was kind but shrewd, the eyes of a man who'd seen everything and still expected the best from those under his watch.

"Chief Webber," Nate said, stepping forward and extending his hand. His grip was firm, professional, but not without respect.

Webber's smile was small but genuine as he shook Nate's hand. "Welcome to Seattle Grace. I trust your trip wasn't too rough?"

Nate offered a polite smile in return, the kind that gave away nothing. "The trip was fine," he replied smoothly.

Webber's eyes flicked over Nate, assessing. It was subtle but thorough, as though he were piecing together who exactly he'd brought into his hospital. "Jet lag can be a killer," he added, almost conversationally. "But I suppose you're used to being pulled in every direction. With your credentials, I imagine you've learned to adapt."

"I try," Nate said simply, his voice betraying none of the exhaustion he felt. It wasn't the trip that had worn him out. It was the rest of it; the packing, the leaving, the closing of one chapter without being certain what the next held.

"Well, I'll give you the full tour later," Webber said. "But for now, I'll give you the short version: Seattle Grace is a teaching hospital, but we don't let that get in the way of delivering the best care possible. We expect a lot from our staff, and we hold each other accountable. From what I've heard about you, I think you'll fit right in."

Nate raised an eyebrow, a flicker of curiosity in his expression. "From what you've heard?"

Webber's smile widened just a fraction, and there was a hint of amusement in his tone. "Derek Shepherd had plenty to say about you. All good, I assure you. He was quite insistent that we bring you on board."

That gave Nate pause, though he masked it well. His polished exterior didn't falter, but the words settled uneasily in his chest. Derek Shepherd had recommended him. Nate wasn't sure how to feel about that.

"Derek mentioned we'd worked together?" Nate asked, keeping his tone neutral.

Webber nodded. "He spoke highly of your skills and your instincts. Said you'd be an asset here."

Nate's lips curved into a polite smile, though his thoughts were a little harder to contain. "I hope I live up to expectations."

"I have no doubt you will," Webber said with the confidence of someone who rarely doubted his own judgement. He glanced over Nate's shoulder and smiled. "Speaking of Derek..."

Nate turned before he could stop himself, and there he was.

Derek Shepherd.

It had been years since Nate had last seen him, but Derek looked almost exactly the same. His dark, wavy hair was perfectly tousled, and his smile still had that easy charm that used to make Nate roll his eyes. But there was something different now, a tension in his shoulders, a wariness in his expression that Nate hadn't seen before.

"Nate," Derek said, his voice steady but softer than Nate remembered.

"Derek," Nate replied, his tone measured.

There was a beat of silence, and Nate felt the weight of Webber's gaze flickering between them, assessing the history neither of them had acknowledged out loud.

"Well," Webber said, clearing his throat and stepping back, "I'll leave you two to catch up. Nate, we'll touch base later. Again, welcome to Seattle Grace. We're lucky to have you."

As Webber walked away, Nate turned back to Derek, his sharp gaze locking onto Derek's face.

"You haven't changed," Derek said finally, his tone quiet but tinged with something Nate couldn't quite name.

Nate tilted his head, his lips curving into a faint, bitter smile. "You have."

The words landed with more weight than Derek had expected, and for a moment, his mask slipped. He opened his mouth to respond, but Nate cut him off.

"Let's skip the pleasantries," Nate said, his voice crisp. "Why am I really here, Derek?"

Derek's expression flickered, guilt flashing across his face before he steeled himself. "Because you're good at what you do," he said simply.

"That's not what I'm asking," Nate replied, his tone sharper now.

Derek sighed, running a hand through his hair. "It's not like that, Nate."

"Isn't it?" Nate asked, taking a step closer. His voice was low but sharp enough to cut through the noise around them. "Because it feels a hell of a lot like you orchestrated this."

"I didn't," Derek said firmly. "I recommended you because I know you. I know how good you are. That's it."

Nate's eyes narrowed. "You really expect me to believe that? After everything?"

Derek looked away, his jaw tightening. "I'm trying to move forward, Nate. This isn't about... us."

The word lingered in the air, heavy with everything unsaid.

"Right," Nate said, his voice quieter now but no less pointed. "Because that's all ancient history to you, isn't it?"

Derek flinched, and for a moment, he looked like he might argue. But then his shoulders sagged slightly, and he looked at Nate with an expression that was almost pleading. "I'm trying," he said softly.

"Try harder," Nate shot back, his voice cold.

The tension between them was unbearable, an invisible line pulled taut and ready to snap.

"We should talk," Derek said finally, his voice tight.

Nate's lips pressed into a thin line. "There's nothing to talk about."

But the way his heart was racing said otherwise.

"Let me show you around," Derek said, his tone firm but still hesitant, as though he knew Nate might refuse.

For a moment, Nate considered walking away. But he didn't. Instead, he nodded stiffly, following Derek down the hall without another word.

The hospital buzzed around them, but it felt distant, like a world apart from the storm brewing between them.

It's far gone into Nate Mercer's first shift, he's not really paying attention, the chaotic rhythm of rushing nurses, hissing ventilators, and the muted hum of a thousand problems waiting to be solved. Nate found the chaos to be grounding, in an odd way. The sheer predictability of its unpredictability was something he had learned to rely on. Patients would crash, charts would pile up, and the fluorescent lights would buzz endlessly above.

Nate was leaned over the lightboard in the surgical wing, fingers tapping idly against the edge of the screen. Scans flickered in cold monochrome, a tangle of shadows and lines that held the answer to a case he'd been chewing on for hours. A woman in her late fifties, complaining of intermittent numbness in her extremities. Her CT scan looked clean, but something about it gnawed at him.

He squinted, tracing the contours of the scan, his mind running through a number of possibilities. An aneurysm? Maybe a spinal issue? He leaned in closer, losing himself in the quiet puzzle in front of him.

And then he heard it.

"What?" Bailey's sharp, voice broke through his thoughts.

Nate didn't look up. Bailey's no-nonsense demeanour was the backbone of the surgical floor, as he had heard, and it wasn't unusual to hear her snapping at an intern or two.

"Katie's parents have questions," came the reply, quieter, more tentative. Nate's eyes flicked to the side, catching a glimpse of Meredith Grey, standing stiffly in front of Bailey. "Do you talk to them, or do I ask Burke?"

He didn't know much about her, only what he'd picked up in passing, a new intern, quiet but not timid, with the kind of tired eyes that spoke of long nights and longer worries.

"No, Burke's off the case," Bailey told her. "Katie belongs to the new attending now. Dr. Shepherd. He's over there."

Nate's gaze flicked up, following Bailey's pointed gesture toward the far end of the room.

Meredith took a few tentative steps in the direction Bailey had indicated, but then she froze. Her body stiffened, her head tilted slightly as if she were bracing for impact.

Nate straightened, his curiosity piqued. His eyes followed hers to where Derek Shepherd stood, casually,  deep in conversation with another doctor.

And then it clicked.

He saw it, the slight widening of Meredith's eyes, the way she suddenly turned, retreating as if the ground under her feet had turned molten. Derek glanced up, a flicker of recognition crossing his face as he did a subtle double take.

Nate tilted his head, watching the scene unfold like a silent drama.

He recognized that look on Derek's face, a flash of something too personal, too raw for a professional setting. Whatever had just happened wasn't some casual coincidence. There was history there, and it was written across both their faces in capital letters.

"Interesting," he murmured to himself, his voice low enough to be drowned out by the hum of the lightboard.

Bailey, oblivious to the undercurrent between her intern and the new attending, brushed past Nate on her way to wrangle another set of interns. Nate stayed rooted in place, his mind already spinning.

"Dr. Mercer," a nurse called from behind him. He turned, offering her a distracted nod as she handed him a chart.

"Thanks," he said curtly before returning his attention to the scans in front of him.

But he wasn't really seeing them anymore. Instead, his mind lingered on the look Meredith gave Derek, the way she turned to leave before she even got within earshot.

He rolled his shoulders back, trying to shrug off the nagging sense of unease settling in his chest. Intern drama wasn't his problem. Still, something about the way Meredith's expression cracked just slightly, it stuck with him.

It was chaos in the OR room that both Derek and Nate had been paged to. Meredith was standing there flustered as well as the few nurses. All he could think of what what the hell happened, but Derek beat him to it verbally,

"What the hell happened?"he exclaimed, clearly agitated.

Meredith looked panicked, "She had a seizure-" she began, but was quickly cut off by Derek.

"A seizure?"

"Her heart stopped."

"You were supposed to be monitoring her." Derek chastised.

Nate felt extremely awkward standing in the middle of this confrontation, he coughed awkwardly, "Doctor Shepherd, let the intern go, we can handle it from here." He nodded at Meredith, signalling her to go. Once she was out of view, he spoke up again, "We can take it from here."

Again Nate noticed Derek's lingering glance as Meredith left the OR

It was well past the 24 hour mark of Nate's shift, and after the almost disasterous event's of Katie's surgery, Nate was dreading the confrontation and talk with Katie's parents. He didn't have to wait to find out too long as, as he turned the corner, he saw Derek talking with her father, he already heard raised voices, which wasn't a good sign.

"You said it was a seizure disorder. Now you're saying it isn't?" Katie's father asked,

Derek sighed, "I'm saying that I don't know."

"Well, what do you think it could be?" Katie's mother asked,

Derek sighed again in frustration, "I don't know."

"When will you know?" the father asked his voice growing in frustration.

"I don't have an answer for you right now. For now," Derek tried to explain but was quickly cut off.

"Wait one damn minute. We came here because this hospital is supposed to be the best there is in Washington. That's my kid in there. My kid. And you have the audacity to tell me, I don't know?"

"Mr Bryce," Derek responded calmly, in an attempt to dissipate the anger of the situation.

"No, I want someone else. A doctor who knows what they are doing. You get me someone else. Someone better than you."

"I can assure you that I am working hard on Katie's case." Derek argued.

"No, you're not." the father snipped back bluntly, "If you were, you'd be able to give me some answers."

Nate should've stepped in minutes ago, before the conversation got tense. But, Derek is an grown adult. He can handle these conversations himself.

Nate cleared his throat as he stepped into the room, his voice cutting through the tension. "What's going on here?"

Derek glanced at him, relief flickering across his face for half a second before it vanished. "Katie's parents have questions," he said simply.

"Questions?" Nate echoed, his brow furrowing as he stepped closer. "You mean yelling at their daughter's attending isn't clearing anything up?"

"He's not answering us," Mr. Bryce snapped, turning his frustration toward Nate without hesitation. "We deserve answers."

"You do," Nate said evenly, his voice calm but firm. "But yelling won't make them come any faster." He glanced at Derek. "What's the update?"

Derek opened his mouth to respond, but Mr. Bryce cut him off. "The update is that he doesn't know what's wrong with my daughter. He doesn't know anything."

"Mr. Bryce, we are doing everything we can," Derek started, but the man's voice rose over his.

"No, you're not! If you were, you'd have answers. You wouldn't be standing here telling me you don't know!"

Nate took a step forward, inserting himself between Derek and Mr Bryce. His tone sharpened just slightly. "Mr Bryce. I understand that you're scared. I'd be scared too if I were in your shoes. But Derek Shepherd is one of the best neurosurgeons in the country. If anyone is going to figure this out, it's him."

"Then why hasn't he figured it out yet?" Mr Bryce shot back, his voice trembling with emotion.

"Because medicine isn't magic," Nate said bluntly. "It's science. Katie's case is complicated, but we are not giving up on her."

Mrs Bryce, who had been silent until now, stepped forward, her voice quieter but no less tense. "What happens if you don't find out what's wrong?"

Nate's expression softened slightly as he turned to her. "We will find out," he said firmly. "It's not a question of if. It's a matter of when."

"But when?" Mr Bryce demanded, his voice breaking slightly. "How much time does she have?"

"She's stable for now," Derek said, finally finding his voice. "We're running more tests. I promise you, we're not stopping until we have answers."

The room fell into a heavy silence. Nate could feel the weight of it pressing down on his chest, the sheer gravity of their fear.

"Now that's sorted, I must excuse my myself." Nate excused, before heading of back down the corridor.

Derek was losing his focus, and Nate couldn't stand it.

The door to the on call room slammed shut behind Nate, the sharp sound reverberating off the cold, sterile walls. The force was deliberate, more than he intended but perfectly fitting for the storm that churned inside him.

Derek startled, jerking his head up from where he sat on the cot, his legs spread, elbows resting on his knees. He looked like a man caught off guard, though the tension in his shoulders betrayed the familiarity of conflict. His brows furrowed in confusion, but Nate could see the flicker of something else beneath it. Guilt, maybe.

"Nate?" Derek asked, his voice a mixture of surprise and defensiveness.

Nate barely gave him a chance to continue before stepping into the room, closing the distance between them in long, purposeful strides. His heart was pounding, the anger rising in him like a tide he could no longer hold back.

"What the hell are you doing, Derek?" Nate demanded, his voice low but carrying the sharp edge of a blade.

Derek straightened, his confusion deepening. "What are you talking about?"

Nate's lips twisted into a bitter smile. "Don't play dumb with me. That intern. Meredith Grey. What's going on with her?"

Derek's jaw clenched, the line of his mouth growing taut. "Nothing," he said flatly, though his eyes darted away for a fraction of a second, a tell Nate knew all too well.

Nate's laugh was short and harsh, filled with disbelief. He stepped closer, shaking his head. "Don't lie to me, Derek. I saw it. The way you looked at her. The way she looked at you."

Derek's hands dropped to his sides, his fingers curling into fists. "It's not"

"Don't you dare say it's nothing," Nate snapped, cutting him off. His voice rose, his anger spilling over, "Because I know that look, Derek. I know it because I've seen it before. Felt it."

That last word landed like a punch, the weight of it hanging heavy in the air between them. Derek stiffened, his expression faltering for just a moment before he forced it back into something guarded and unreadable.

"Oh, my God," Nate said, his voice a mix of disbelief, realisation and venom as he took another step forward, now inches from Derek. "You slept with her, didn't you?"

Derek's eyes narrowed, his expression hardening. "That's none of your business."

"None of my" Nate's voice cracked, and he let out another bitter laugh. "Are you kidding me? You're the one who called me here, dragged me back into your orbit, and now I find out you're screwing interns?"

"It's not like that," Derek spoke, his tone quieter now, but no less strained. His defences were cracking under Nate's relentless stare, and for once, Nate could see the conflict playing out on Derek's face.

"Then what is it like, Derek?" Nate pressed, his voice dropping into something softer but no less cutting. "Because from where I'm standing, it looks a hell of a lot like history repeating itself. You get close, you make them believe they're special, and then"

"Stop," Derek interrupted, his voice sharp and commanding. His eyes burned with an emotion Nate couldn't quite place. "Don't do that. Don't twist this into something it's not."

"Then tell me what it is!" Nate shouted, his frustration boiling over. "Because all I see is you making the same mistakes. Over and over again."

Derek was silent for a long moment, his gaze shifting to the floor as if it could shield him from the weight of Nate's accusations. Finally, he spoke, his voice tight. "I didn't ask you to come back here to do this."

Nate scoffed, taking a step back, the bitterness in his expression cutting deeper than any words. "No, you didn't. You just made it impossible for me to say no. Like you always do."

"That's not fair," Derek said, his voice rising as he stood. His full height and the fire in his eyes might have been intimidating to anyone else, but Nate met it without flinching.

"Fair?" Nate repeated, incredulously. "You want to talk about fair? Fine. Let's talk about fair. You walked away from me, Derek. Left me with nothing but an empty promise. And now, years later, you're here, playing house with an intern while pretending you're still the noble surgeon everyone looks up to."

"I'm not playing house," Derek snapped, his voice cracking with frustration. "And you don't get to stand there and judge me like you've never made mistakes."

"This isn't about my mistakes," Nate shot back, his voice like ice. "It's about yours. You're dragging Meredith into something she doesn't deserve. Something you know damn well will end in disaster."

Derek's face crumpled for a split second, the mask slipping just enough for Nate to see the guilt underneath. But then, just as quickly, it was gone. "You don't know what you're talking about," Derek said, his tone firm, though it lacked conviction.

"I know you," Nate said quietly, the anger in his voice replaced by something softer, sadder. "I know what you do when you're hurting. You throw yourself into someone new, someone who doesn't know you well enough to see the cracks."

Derek's eyes fell to the floor again, and Nate felt a pang of something he didn't want to name. Sympathy, maybe. Or regret. It didn't matter. Not now.

"You haven't changed at all, have you?" Nate said, his voice barely above a whisper.

Derek looked up at that, his expression hardening again. "You don't get to say that to me. Not after everything."

Nate tilted his head, a bitter smile on his lips. "After everything?" he repeated. "You're right. I don't get to say anything. Because you made sure of that when you walked away without looking back."

The silence that followed was deafening. Derek's shoulders sagged slightly, and for the first time, he looked small. Defeated.

Nate took a step back, shaking his head. "I hope she knows what she's getting into," he said softly, his voice filled with something Derek couldn't quite place. "Because she deserves better. And so did I."

With that, Nate turned and walked out, the door clicking shut behind him with a finality that left Derek sitting on the cot, his head in his hands.

The room was packed, buzzing with tension. Interns clustered together, their faces apinted with exhaustion. This was their moment of impressing the attending doctors, and proving they belonged here. Nate leaned against the back wall, arms crossed, watching the scene unfold. He had hoped Derek would've handed Katie's case to him, but after their argument there was no chance of that happening, but nevertheless Derek had asked him to be there, so he was.

He was also there because he didn't trust a room full of fresh interns to help solve a case as critical as Katie Bryce's.

"Does anyone know why we're here?" Cristina Yang's sharp voice cut through the murmuring crowd, a touch of impatience curling the edges of her words.

The door opened and Derek Shepherd strode in with his usual confidence. "Well good morning. I'm going to do something pretty rare for a surgeon." he started, "I'm going to ask interns for help."

Nate's brow lifted slightly. Rare, huh? He rolled his eyes subtly, leaning back further against the wall. Derek caught the movement and shot him a knowing glance before continuing.

"I've got this kid, Katie Bryce. Right now, she's a mystery. She doesn't respond to her meds. Labs are clean, scans are pure, but she's having seizures. Grand mal seizures with no visible cause."

The room stilled, as the interns watched Derek intently.

"She's a ticking clock," Derek said, pacing slightly. "She's going to die if I don't make a diagnosis. Which is where you come in. I can't do it alone. I need your extra minds, extra eyes. I need you to play detective. I need you to find out why Katie is having seizures."

Nate shifted his stance, his arms uncrossing slightly. He didn't like this, throwing fresh interns into such a high stakes situation. It felt reckless.

Derek, however, was in his element. "I know you're tired, you're busy, you've got more work than you can possibly handle. I understand." He paused for effect, his voice softening. "So, I'm going to give you an incentive. Whoever finds the answer rides with me. Katie needs surgery. You get to do what no interns get to do: scrub in to assist on an advanced procedure."

Bailey stepped forward, handing out charts. "Here's Katie's file. The clock is ticking, people. Move."

As the interns scrambled for the charts, Nate could only think about what was going to wrong.

Derek walked over to him, a faint smile tugging at the corner of his lips, "You look unimpressed, Mercer."

Nate's gaze didn't waver, "You're putting a lot of faith in people who don't know what they don't know yet."

Derek chuckled softly, "You don't think they're up to it?"

"I think they're interns," Nate replied flatly. "It's more or less their first day and you've handed them a case that could kill a patient." He paused, "I'm not saying they can't figure it out, but you're playing a dangerous game, Shepherd."

Derek's smile didn't falter, "You were an intern once."

"I was."  Nate replied evenly. "I know the pressure made me better. But I know the difference between pressure and recklessness." He glanced towards the interns who were already flipping through Katie's chart with furrowed brows.

Derek exhaled sharply, dragging a hand through his hair. "This isn't about the interns is it?"

Nate's eyes narrowed, "What are you talking about?"

"You're pissed because I didn't ask for your help." Derek remarked bluntly. "That's really what this is about."

For a moment Nate didn't respond. The air between them crackled with tension.

"Maybe I am," Nate admitted finally, his voice quieter. "But can you blame me? I'm right here. Hell, you even recommended me to Webber. I have the experience, the skill and the time to focus on this case. But instead, you handed it over to a new group of interns."

Derek's shoulders sagged slightly, "Nate"

"I'm not done." Nate interrupted, his voice rising again, "You didn't ask for my help because you didn't want to. You wanted the glory of solving this case yourself, with a side of mentorship to make you look like the good guy. And you know what? Fine. But don't expect me to stand here and pretend I'm okay with it."

"I'm trying to teach them," Derek sighed in anger, "They need to learn how to handle cases like this."

"But not today!" Nate barked, the anger in his voice caught Derek off guard. "Not when there's someone's life on the line."

For a moment, neither of them said anything.

Finally Derek spoke up, his voice softening. "You're right. Maybe, I should've asked for your help."

Nate blinked, his anger cooling fractionally.

"But I didn't," Derek continued, his tone steady, "Because I know you, Nate. You would've taken this case, locked yourself in a room, and pushed everyone else out, including me."

Nate opened his mouth to protest. But immediately stopped. Derek was right, that is exactly what he would've done, and he hated how Derek's words hit uncomfortably close to home.

"You're not wrong." Derek spoke, as if reading his thoughts. "But this case, they need to learn," he continued as he gestured towards the interns.

Nate's gaze softened ever so slightly, but his jaw remained tight. "Just don't screw this up," Nate resigned, "If not you'll never forgive yourself."

Derek nodded, "I won't."

Nate didn't reply, his eyes lingered on Derek for a moment before he turned and walked away, leaving Derek standing alone.

AUTHORS NOTE.

hello! thank you so much for reading this chapter. i love nate so much and i'm so excited to bring him into grey's! there is already so much tension already!

i tried to make this chapter show nate's dynamic with the world around him, and how he is going to try and integrate himself in seattle grace.

thank you for reading this chapter, and if you liked it please like or comment 🙏🙏