It happens so fast, the hook of her former captain's arm around Castle's neck, the gun that rises to his temple, everyone alert and standing and frozen in place.
"Captain," Esposito shouts, his own gun rising, but Roy fastens his finger to the trigger.
"Stand down, Soldier. I don't want to draw attention, but I will," he threatens with an arch of his brow. "And it won't be hard to explain away. These three new survivors show up and suddenly, our allies are dropping like flies, and there's only one way to handle traitors. But of course, being so loyal to your former teammate, you defend her, her people, without hesitation. So, I have to kill the entire room. And I will."
Esposito's lips purse, but his gun returns to his side. "Yes, sir."
"Let him go," Kate snarls, her fingers bruising into Alexis's shoulders, her heart pounding at his daughter's back. Castle is looking at her with restrained dread, attempting a calm façade for them both, but she can read between the lines, can see that he doesn't think he's going to make it out of this one and that's just not acceptable.
"See, I'd like to, but that one," Montgomery – or whoever, whatever, is inside of Montgomery – says, glaring down at Alexis. "Is becoming quite the issue. You really think I didn't hear you sneaking around outside my office?"
"Go to hell," Alexis growls, her knuckles shining ivory at her sides.
"Hell does not exist for my kind."
"What did you mean," Ryan pipes up, his voice controlled, but small. "When you said Roy didn't want you to do this? Is he… are you – what are you?"
"You humans are so dense," he sighs, tightening the arm around Castle's neck. "When we take these bodies, the person they belong to still remains. But they're silenced, repressed to nothing more than an irritating little voice within the brain. And no, before you ask, once inhabited, there is no way to bring the person back unless the entity inhabiting them willingly leaves, which I can assure you will not be happening in this scenario."
"How'd you take over our captain?" Esposito asks, his voice stone cold, his eyes intent. Beckett knows that look and meets Ryan's gaze, gives him the subtlest of nods while the enemy's eyes are averted.
"There always has to be a martyr," the faux Montgomery explains with exaggerated patience. Apparently, aliens are quite the pretentious assholes. "Always has to be someone on the inside and unfortunately, that had to be me. I've been with you since the evacuation from the Twelfth. I needed the weakest link, Roy Montgomery provided me with one."
"Yeah? And why stay with us this long? Why not kill us all the second we got here?" Esposito demands while Ryan rises slowly from his seat at the control panel, California still fighting to stay on the grid above.
"You all think you're so smart, as if you could really find a place on this earth where we wouldn't track you. This entire time, I could have blown the whistle, yes, but we wanted time to study, to learn in person, before we finally eliminated what was left of your species."
"Why?" Castle grits out.
The face of Roy Montgomery smirks. "So we could destroy the last of you from the inside out."
Ryan body slams the invader from the side, dislodges the gun from Castle's temple, and Kate lurches for him, jerks Castle behind her and tackles Montgomery to the ground. It's Esposito's gun that fires, the silencer muting the shot, and the man beneath her and Ryan gasps, stares up at them both with wide eyes that flash like a malfunctioning computer.
"Won't win," he wheezes, blood trickling down the side of his face from the bullet lodged into his temple. "Win. Don't. Can't-" The surges of light in his eyes die, but the corner of Montgomery's mouth twitches and Kate knows with certainty that the last time Montgomery speaks, it's as himself. "T-time to… make your stand."
The last of the light, the flicker of what was left of their former captain, finally goes out, the two beings intertwined into one finally dead. Esposito offers his hand to Ryan and Castle's fingers curving over her shoulder draw her back, his touch breaching the cascade of horror overtaking her system.
Kate hauls herself to her feet by her grip on his shirt, wraps her arms around his neck and buries her face against his throat.
"Are you okay?" she breathes, pulling back to feather her fingers at his throat, up to his temple where the barrel of the gun had bit into his skull.
"Kate." Castle catches the frantic flutter of her hand, pins her palm to his cheek, and she chokes on the unexpected lump forming within her throat. Too close, it had been too close, he'd almost- "I'm fine. I'm fine, I promise."
But he's not, and neither is she, neither is the girl watching them with glassy eyes or the men standing dumbstruck and broken at her back. They've been struck hard with an unexpected betrayal, left shocked and without a leader, all while the last of mankind is falling apart for a second time.
But no, not again. Mankind would not go down like this.
"We'll have to fight," Kate murmurs, smoothing her thumb along the corner of Castle's mouth before lowering her hand from the freshly shaven skin of his cheek. "Ryan, Espo, you said there was advanced military weaponry here?"
"Not sure how effective it'll be, but it took down a good number of them last night," Esposito nods, returning his sidearm to its holster.
"It'll have to be good enough," Kate decides, glancing back to the fighting flicker of Los Angeles on the screen. "Is there a way to warn the remaining cities?"
"On it," Ryan mumbles, scrambling over Montgomery's body, back to the control panel and the tossed headset.
"They have us like sitting ducks here, we'll need to evacuate, quickly but quietly. Set up a temporary headquarters elsewhere while we wait for them to strike," Kate instructs, pacing away from Rick and Alexis, scraping a hand through the rioting locks of her hair, still damp from the shower. "We'll raid Montgomery's office. It's unlikely the - the Outsider kept any information on hand, but it's worth a look."
"I can help with that," Alexis quips, stepping up from behind her father with bright blue determination blazing in her eyes. "I'm good with details, the little things."
Kate hesitates, glancing over the girl's head for Castle's gaze, but earning a nod of acceptance.
"There's no one I'd trust more with the job," she murmurs, squeezing Alexis's shoulder. Her lips quirk, but his daughter doesn't smile, starting past Kate with her head held high as she exits the control room, bounds up the stairs.
Esposito casts his eyes to the closed doorway before turning his gaze on Castle and Beckett, his lips set in a thin line. "It's going to be a war and we're going to have to get our hands dirty."
"What does our armory look like?" Kate inquires, dividing her attention between Ryan's fervent work at the computer, Esposito's calculations, and Castle's nervous energy at her back.
"It's impressive, but I don't know if it's enough. Montgomery probably gave them our entire inventory-"
"It wasn't him," Beckett murmurs, crossing her arms over her chest and managing a steady swallow, refusing to spare a glance at the dead man still on the ground between them. "Not completely him."
"He didn't choose this, didn't want it," Castle reminds them both, his voice solemn, reassuring, and she wants nothing more than to rewind to a few hours back, crawl back into that bed upstairs and down the hall with him. To feel the closest she has to safe in months. "There was nothing he could do to stop it."
"This means… it means Lanie was still in there when I killed her," Esposito breathes, squaring his jaw so harshly, the angle of bone threatens to puncture through his skin. "I killed her."
"Same with my mother," Castle whispers and Kate whirls around, stares up at the ashen face of the man she loves, and her chest clenches, torn between rage and sorrow.
It would have been enough to invade the planet, eradicate the earth of its ruling species, but the Outsiders had made it personal, had done more than kill the human race. They were torturing them, destroying them from the inside out, just like the one inside of Montgomery had said.
She wants every last extra terrestrial asshole eradicated.
"No, no, both of you know that's not true," she argues, hooking her fingers in the front belt loop of Castle's pants. "Montgomery, Lanie, your mother – they wouldn't have wanted to keep going like that. They weren't them anymore and there was no way to get them back, to save them. You can't carry that kind of guilt over something you couldn't have stopped."
Esposito slams his fist into the doorframe, startling Ryan, but Castle merely averts his eyes to the floor, silent in his grief.
"And I told you," Kate whispers, only for him, detaching her fingers from the loop of fabric on his pants to curve her palm at his nape. "I told you to do exactly the same thing if it happened to me or Alexis. Because it's the right thing, Rick. Anything is better than becoming one of them."
"I'm getting chatter from LA, they're fighting them off," Ryan announces, his eyes wide, the hopelessness that had drenched his irises in a dull shade of grey washed away by the burst of mercurial blue. "They - they've managed to figure out the weakness. Holy shit."
Castle clutches a hand at her hip, strong fingers around the sharp bone, the hope Ryan exudes catching but cautionary. They can't afford to trust that their allies have found the Outsiders' weakness, a way to end this, not yet. Not until-
"Air raids," Ryan presses the headpiece in tighter against his ear, his eyes closed and his brow furrowed in concentration. "The Outsiders, the way they obtain nutrients is through the skin, absorbing it. The LA survivors are literally flying over California and-"
The door slams open and Alexis stumbles inside, a file clutched to her chest. "We have to poison them."
Ryan snaps his fingers. "Bingo."
Esposito had raced out of the room to prepare the single aircraft they have possession of above ground the second after Ryan and Alexis had both explained the newfound solution, the remaining sectors now communicating with Ryan and what's left of Los Angeles to do the same. But there will still be a battle, a fight to destroy those of the Outsiders who may survive the airborne attack, and Kate has to bite her bottom lip to stop her fingers from trembling as she secures the bulletproof vest over her chest.
They go still at the sight of Castle reaching past her for a larger one, slipping his arms through the holes and beginning to fasten the side straps. He was supposed to be with Alexis, going over the plans for the air raid that's scheduled to take place in a matter of hours, the second the Outsiders make the first move.
"Castle." He doesn't look at her, his eyes on the work of his vest, just like everyone else in the armory, preparing for humanity's last stand. "What are you doing?"
"I'm going out there with you," Castle states, his voice low but firm, leaving no room for argument.
Unacceptable.
Kate drops her arms to her sides, her vest still half undone, and crowds into his, ducking to catch a glimpse of his face and covering the work of his hands with her own. "Rick, you can't-"
"You are not doing this alone," he hisses, his eyes fierce with protest, but his hands are steady when they slip from beneath hers, reaching forward to finish securing her vest instead. "We're - we're partners. We're a team."
"I told you from the moment we met that strength isn't in numbers, Castle. Some things have to be done alone," she murmurs, her hands rising to cup his face as his head begins to shake, but he curls his fingers around the bones of her wrist.
"Not this."
"What about Alexis?" she demands, aware that it's a low blow for him, but he has to think of his daughter, has to put the needs of his child before all else.
"Alexis would never let you do this on your own either," he growls, but his entire face is a compromise of pain and fear, a contrast of hope and dread. "Besides, she wants to be on the plane with Ryan. It's safer there anyway."
"Exactly why you're going to be there with her."
Castle tangles his fingers in the loose strands of her hair, not yet tied back into the necessary braid she'll require, and cradles the back of her skull in his large palm. She already knows she's not going to win this one, that no matter how hard she tries, he'll stay true to his word, ensure his daughter's safety and stay with her until the end.
"I can't lose you."
Beckett purses her lips, flicking her eyes past his shoulder to the few remaining survivors left in the room, but they don't spare them a glance of attention as they trickle out of the room, bodies shielded in armor and laden with weapons.
"I can't lose you either. I won't - I won't survive it, Castle," she confesses through grit teeth, but her eyes are burning, stinging with tears, and she squeezes them shut, wills the moisture to dissipate.
"That's why we're sticking together. I have your back, you have mine, and that is how we both survive this. It's how we've made it this far."
"And Alexis?" she questions, her voice wavering, her eyes still closed, his words and the warmth of his touch her only anchors.
"Will be safe, safer than us. Regardless of what happens, she'll have a chance."
She forces her eyes open to meet his, to memorize the soft shade of cerulean and the half smile on his lips. "And if we don't make it?"
"She knows the risks. She doesn't like them, neither do I, but she knew there was no stopping you and like I said, Alexis is about as accepting of you going out there without your usual backup as I am," he quips, shrugging his shoulder with a boyish grin and she wants to hit him, to lecture both him and his daughter, to kiss him, to cry.
"Kate," he sighs when that last one becomes a reality, his fingertips catching her tears. "For the record, I don't plan on allowing either one of us to die, but I am not leaving you alone. I can't. End of story," he murmurs, his thumb traveling to caress the sensitive flesh behind her ear. Kate growls, loud enough for only him to hear, and surges up on the toes of her boots, bruises his mouth with a kiss and allows the last of her tears to spill onto his cheeks.
"I hate you," she huffs, but his lips split into a smile against hers.
"Love you too, Beckett."
The body armor weighs heavy along his chest, his arms and legs, and the necessary discomfort aids in distracting him in the hours leading up to their final attack, during their departure from the bunker, back into the dark cavern of the subway tunnel. Castle's heart is pounding so violently in his chest now, rattling the cage of his ribs, that he has to strain to hear the commands Beckett is giving to those assigned to their 'troop' while they huddle in the pitch blackness. Kate is a natural leader, that much he can see, and he says a silent prayer of gratitude for all of the training she was able to receive prior to this, for the instincts she was born with that have kept her alive this long.
He meant what he said to her in the armory before they had marched up the stairs, gone over the plan until it was engrained into their skulls, and said the most heart-wrenching goodbye to his daughter that he's still trying not to think about. He has no intentions of dying today, but he does have a priority, and that is the woman standing beside him.
As long as Kate lives, that's all that matters.
"We wait for Ryan's signal," Beckett states, holding up the battery powered walkie talkie, one of the three that have been divided between the group leaders of herself, Ryan, and Esposito. "Once the air strike is a go, we head to the surface, open fire on any that are still standing. Simple enough, but don't let your guard down. Even if we do overpower them, these things are inhuman and so are their weapons. And most importantly, remember to always aim for the head. Kill the brain."
The crowd of twenty nods, some brimming and ready for the showdown, others trembling with dread. Castle is somewhere in between, eager for all of this to end, afraid of what a conclusion will entail.
The street above them begins to shake and Kate nods towards the ladder up ahead.
"Everyone stay calm, we know their playbook for once," she reminds the group as one by one, they begin climbing to the steel ladder that leads upwards to the subway station. "This is just the first wave. Their way of hitting anyone above ground."
The attack will take place in the center of Manhattan, posed to stretch outwards and decimate the entire island. At least, that's what they were predicting after a brief study of Houston's takedown, along with DC's and Atlanta's. Los Angeles survivors were still standing despite a loss in half their group, but there were far more extra terrestrial casualties and reinforcements were taking the remaining planes over the states, infusing the air with various blends of harmful chemicals that humans can withstand. But not the aliens.
Ridiculous, Castle thinks, that despite being potentially thousands of years more advanced than the human race in practically every way, the aliens had yet to determine a way to protect their absorbent flesh from potent materials. Hell, Boston had just taken out at least half of their threat with Windex.
"Rick?" Castle glances up from the back of the line, Kate standing beside him with her fingers latching onto his belt loop out of habit. Her eyes are a soft hazel in the darkness, sparks of gold and traces of green luminescent in the shadows, and he commits them to memory, afraid it may be the last time he sees them. "You okay?"
"Nervous," he confesses with a shrug, the machine gun on his shoulder bumping against his hip. "You?"
"The same," she sighs, leaning into him, and Castle drops his forehead to hers, relishes in the subtle scent of cherries that she has somehow managed to maintain, the aroma he remembers from her apartment, when everything seemed far easier to live through. "But Castle, no matter what," Kate murmurs, her free hand rising to his jaw, her thumb tipping his chin upwards so he can meet her eyes. "Our plan from the beginning remains the same. You stay right next to me. At all times."
"Easiest instruction I've ever received," he echoes with a grin, smearing his lips to her skin as the last of their group ascends to the surface.
Castle climbs the ladder after her, sticking close and sending up comments about the view that have her huffing in feigned irritation, greeting him with a smile when she offers her hand from the top, hauls him over the ledge and onto the grimy subway floor with her.
A violent crash breaches the relative quiet, the earth shaking once more before all goes still.
Her radio squawks at her hip, Ryan's voice penetrating the silence.
"We just hit them with our first wave. Enemy's aircraft is down and so is the majority from an aerial viewpoint. Next wave is in twenty. Proceed with caution and remember to secure your face guards."
'Face guards' was a fancy term for the scarves, bandanas, and even rags each person had tied around their neck, now positioned to cover their noses and mouths, to prevent the inhalation of the chemicals in the air. The mixtures of poisons may not necessarily be lethal to the human race, but inhaling copious amounts of chemicals could still do internal damage they'd all rather avoid.
Kate takes a deep breath and draws her scarf over her nose, motions towards the entrance before she looks to him with her eyes sharp and blazing with determination. "Ready?"
"I'm with you," he nods, following the rest of their group towards the light of the stairs.
The streets are a mess, just as they have been for months now, cracked and abused from explosives, littered with trash and remains, but today, the air is clouded with dust, heavy with the stench of bleach. He can see the Outsiders' aircraft from the subway entrance, nothing like the saucer he had imagined and seen in movies before, but instead sleek like a fighter jet, large enough to hold many, but thin enough to navigate with ease.
Their team divides into groups of two, taking cover behind buildings and automobiles, Castle and Kate slipping into an empty alleyway, crouching behind a dumpster. The lack of movement above ground is eerie, seems to last longer than the two minutes it actually does before shots ring out and the screams begin, both human and not.
"Remember, poison first," Kate whispers, her finger tightening around one of the two guns in her possession, one with bullets, another that resembled a super soaker, filled to the brim with pesticide.
Castle nods his understanding and inches closer towards the edge of the alley, sticking close to the wall with Kate. She sneaks a peek into the street, holds up two fingers (two enemies) and then one (wait).
Beckett positions both hands on the gun infused with poison and he follows her lead, waiting with bated breath for her nod. The aliens that approach are in their natural form, unhidden behind human flesh and faces, and Rick doesn't hesitate to pull the trigger, shooting forth a spray of toxins that coat the pale grey flesh.
The Outsiders release screams that resemble the screeching of a dying animal and he winces, retreating with Kate back towards their cover of the dumpster, but glancing over his shoulder, watching the crumple of the human-like figures to the concrete.
"They look like us," Kate breathes from beside him. "Like – like hybrid versions of humans."
"Only they don't wear clothes," Castle murmurs, wrinkling his nose in disgust.
"The skin must be too sensitive," she reasons, cutting her eyes back towards the street. The pop of gunfire mixes with the hiss of poisonous sprays, the shrieks of agony, and the occasional scream from one of their own.
"How long until Ryan drops the next round of chemicals?" Castle questions, after they've taken out four more of the Outsiders, still hunkered down in the alley, moving too risky.
Kate checks her father's watch. "Less than five. We're holding out well so far and without their transportation, they're trapped here. Just like us."
"Only way out is to fight. "
"They won't win."
"No, not anymore," he concurs, venturing towards the front of the alley once more, craning his neck around the corner and scanning the street ahead. Decimated bodies litter the street, deteriorating on the sidewalks, and Castle glances back to his partner. "Street's clear for the moment, want to move?"
"Yeah, staying in one position for too long isn't my preference either," she mumbles, stepping forward to follow him before the sharp intake of her breath penetrates the air.
His heart stops with dread before he even turns around.
Castle spins on the spot, his weapon raised, just in time to witness Kate go stiff in front of him, her entire body seizing, the sleeve of her shirt wet with the bloom of blood. The flicker of movement from over her shoulder catches his eye and he immediately empties his clip into the Outsider positioned at the opposite entry of the alley. One of the bullets hits home between the human shaped eyes that glitch just once and go dark as the body falls to the ground.
"Kate?" he breathes, jerking forward to catch her when her knees give out, but it's just her arm, why the hell is she-
Her body convulses and Castle drags her deeper into the alley, back behind the shield of the dumpster, and crouches with her splayed over his lap. He quickly cuts away the blood soaked fabric of her sleeve with his knife, but goes still the second her skin is revealed.
Her flesh is alight with pulses of electricity that emanate from the bullet embedded into the muscle of her bicep, rippling shockwaves like tiny bolts of lightning moving beneath her skin and causing her to writhe with barely suppressed cries of pain.
"G-get it - it out," Kate gasps, chokes, her eyes wide with panic and riveted with agony, tears streaking ceaselessly into her hair. "Please, oh god-"
"I'll get it out, I promise," he tries to soothe, but oh, he's panicking, his heart rabbiting in his chest. "Just hold on for me, Kate."
Castle eases her onto the pavement, scanning their surroundings as he braces on his knees beside her, using the torn fabric of her shirt to create a tourniquet just above the wound. He had no medical training, had never thought to practice the removal of a bullet from a human body, but there was no time for hesitation. With each second that passes, another pulse of pain crashes like a wave through Kate's veins and he has to dig it out. He has to.
"Rick," she sobs, her spine arching and he places one hand on her forearm while the other pierces her skin with the tip of his knife, sinking in as close to the visible bullet as possible.
The bullet isn't deep, but Kate is struggling to remain conscious, to bite back her screams, and he whispers apologies as he carves the glowing target out, nudges it upwards with the knife until he's able to ease it through the pool of her blood, up to the surface of her skin.
He hisses when he snags the thing with his fingertips, biting back a shout when it electrocutes him, tiny bites of pain surging up his arm. Shit, that had been inside her.
Castle tears the scarf from his face to wrap it around her arm, applying pressure to the bleeding that evokes a quiet groan of pain, but her eyes are fluttering, her head lolling to the side and no, no he had one job. Keep her alive, all he wants it to keep her alive, he can't-
"Kate," he chokes, gingerly removing the cover from her face, down to her chin. Her eyes are rolling back and he slides a hand beneath her head, cradles the back of her skull in his palm, and strokes his thumb to the papery skin beneath her eye. "Kate, stay with me."
The fingers of her uninjured arm twitch at his thigh, curl into the fabric of his pants. Her lips tremble, words on her tongue, but she's fading, the opportunity to speak abandoning her. Terror is ripping through his guts, consuming him from the inside out, because he doesn't even know the extent of her injuries, the consequence of that superior bullet to her bicep. She could be going into shock, suffering from blood loss due to his amateur medical procedure, or worse. What if the electric waves from that bullet had spread to her heart, fried her muscles, poisoned her blood? The options were endless, each more horrific than the last.
The radio on her hip garbles, words from Ryan he can't make out, and Castle instinctively yanks the thing from her belt, jabs his thumb into the button on the side.
"Ryan, Beckett is down," he gets out into the walkie. "She needs medical attention. She needs - help her, please tell me there's a way to help her."
For one painstaking second, he's met with nothing more than the hiss of static, just before Ryan's voice cuts back in.
"Stay with her. I'm about to drop the second chemical wave, but the radio's enabled with a tracker. Once the area is clear, we'll land as close as possible," Ryan promises, his voice calm, but Castle catches the threat of hysteria hitching his tone an octave higher. "Just stay with her, Castle. She's going to be okay. She'll make it."
Static takes over and Castle drops the radio, hunches over Kate, prepared to cover her from the rain of chemicals that's likely to fall at any moment now. She's still awake, still breathing, but it won't be long now, a matter of seconds until her eyes fall shut and fail to open again.
"We're going to get through this," Castle breathes into her hair, his lips skimming the hot shell of her ear. Fever, she has a fever, what the hell does he do? "The world is going to put itself back together and we're going to have a life, Kate. The life we should have had before all of this. But you have to stay with me."
Her fingers curl at his thigh, her gaze trained on him, but the blinks of her eyes are slowing, her lashes sweeping her cheeks in long strokes.
"Don't leave me now."
A mist of bleach begins to rain down around them, more tortured screeches of alien lifeforms breaching the air, but Castle focuses his attention solely on the rise and fall of her chest, the flood of breath from between her parted lips, and the weakening throb of her pulse beneath his thumb as her fingers go limp at his thigh.