A/N: This is my first season 4 fic. I don't usually like to write pre-season 5, but I got some requests for a Cas and Anna fic, and since she went homicidal in season 5, that meant I had to delve a little further back. So this is for WhiteWolfPrincess95 and jelena789. It's also a slight AU of 4x16 "On the Head of a Pin" so I could work in the protective, big sister Anna feels WhiteWolfPrincess95 wanted. I hope you like it!

Disclaimer: Don't own Supernatural. Some lines from 4x16; they're not mine either. Thanks to 29Pieces for beta reading!

"What We've Become"

Anna stood on the edge of a sleet lined rooftop, looking down into the hospital room across the street. Dean Winchester lay in a mechanical bed, dressed in a sterile white gown with a breathing tube down his throat. Sam sat in a chair at his brother's bedside. He was leaning forward with his elbows on his knees, fists pressed to his mouth in anxious vigilance. Anna watched, an invisible sentinel in the night.

This shouldn't have happened.

She clenched her fists, anger and disappointment swelling in her chest. These were some of the more unpleasant emotions on the spectrum, but when she'd chosen to fall in order to experience humanity, it included both the good and bad.

And so she embraced the bitterness and broaching despair. Castiel could have stopped this. She'd tried to warn him, tried to reason with him. Of all the angels, he had been the one she'd been closest to in all her millennia. He was the one she thought would…

But no. He'd chosen to tow the party line, to blindly follow. Anna hoped Castiel was enjoying the fruits of his spineless labor.

"Anna!"

The mental shout over angel radio startled her. Oh, now he wanted to talk? Well, she had said her piece, and it was clear Castiel didn't want to hear it. She decided to just ignore him, but then there was the more softly sent,

"Anna, please."

She sucked in a sharp breath. Fine. In fact, she wanted to see his face when she confronted him about what happened to Dean. She'd thought Castiel cared about the Winchester, and Anna intended to drive that nail of guilt in as deep as she could.

She flew, landing behind him on the steps of a snowy sidewalk. The streetlight above flickered, and Castiel looked up at it before slowly turning around to face her.

"Decided to kill me after all?" she asked, even though she figured that wasn't what he intended. Deep down, she didn't think him capable of it.

"I'm alone," he replied, and the pain in his eyes suggested multiple layers of meaning in that single phrase.

Anna's chest constricted. She had intended to lay a heap of accusations upon his head, berate Castiel for his inaction, but now she couldn't seem to bring herself to do so. When she looked at him, she saw the fervent and devout soldier she'd climbed the ranks with, the comrade she'd fought beside for eons.

"What do you want from me, Castiel?"

"I'm considering disobedience."

She held her breath. This was the precipice she'd been pushing him toward. "Good."

Castiel gazed at her mournfully. "No, it isn't. For the first time…I feel…" He trailed off and looked away, as though he couldn't find the words. Anna felt a pang of sympathy for him.

"It gets worse." She slowly descended the steps toward him. "Choosing your own course of action…it's confusing, terrifying." She reached out to put a hand on his shoulder. He dropped his dispassionate gaze to the contact. Anna felt something cold and ugly curl in her stomach, and she pulled away.

"That's right," she said bitterly. "You're too good for my help." Why had she bothered to come at all? "I'm just trash. A walking blasphemy." She turned on her heel to leave, only making it two steps before he called her name again, that thread of pleading in his tone. She stopped.

"I don't know what to do. Please tell me what to do."

Anna turned back to face him, feeling a surge of pity and anger toward him. She wanted Castiel to come with her, to join her, to fight for what was right, and not what some angel up the chain of command decided. But she wanted his loyalty and friendship…not his obedience.

"Like the old days?" Anna shook her head. "No. I'm sorry. It's time to think for yourself." And then she flapped her wings before his crushed expression could weaken her resolve. For all the emotions she'd opened herself to from becoming human, sometimes hardening one's heart was the only way to survive.

Castiel stood over the devil's trap, tracing every intricate line with his eyes until he spotted the smeared ink. His gaze tracked the wet stain on the concrete to a dripping faucet. Rotating his wrist, he shut it off.

All the signs were right in front of him, along with half a dozen more subtle clues he'd been too blind to see: Uriel's surprise when Castiel had managed to capture Alastair; his sudden eagerness to work with Dean when Uriel had regarded the human with nothing but open disdain; how long it had taken Uriel when he'd gone to receive revelation—he should have returned much sooner, before Alastair had broken the devil's trap. If Sam hadn't come when he had…

But why? That was what Castiel could not divine. Had it been ordered? Had Castiel remained in the dark because of his demotion? Despite what he'd told Dean, that stung, the thought that his brethren did not trust him. He had not once disobeyed, even with his softening "sympathies."

Castiel could not understand the purpose behind these events, which left him with the uncomfortable and unavoidable question of—was Anna right? Was someone else giving the orders? He almost couldn't bear entertaining the notion, because it meant shattering everything Castiel thought he knew and believed in.

But if she was right…then for the sake of everything he believed in, he had to take action.

"You called?" a deep voice echoed from the outside corridor. A moment later, Uriel entered the prison room.

"What revelation did you receive?" Castiel asked, not looking at him, gaze still fixated on the rusty faucet.

"We are not to heal the Winchester boy."

Castiel's chest tightened, everything within him screaming that this was…wrong. Not heal Dean? After they'd nearly gotten him killed asking—demanding—he do this? How could that be righteous?

"Your pet human will survive," Uriel said, and there was that note of disdain again. "You are needed for more important things. What do you say, Castiel? Will you join me? Will you fight with me?"

Castiel wasn't sure what Uriel was asking; whether Castiel was intending to defy orders and fly to that hospital? Whose orders were they, though?

"Strange," he said. "Strange how a leaky pipe can undo the work of angels." Now he looked at his comrade in arms. "When we ourselves are supposed to be the agents of fate."

"Alastair was much more powerful than we had imagined," Uriel said, shaking his head dismissively.

"No," Castiel interjected. "No demon can overpower that trap. I made it myself. We've been friends for a long time, Uriel," he continued, casually moving around to face the other angel, to look him straight in the eyes. "Fought by each other's sides, served together away from home, for what seems like forever. We're brothers, Uriel. Pay me that respect. Tell me the truth."

"The truth is," Uriel spoke softly. "The only thing that can kill an angel…" his blade slid out from under his sleeve into his hand, "…is another angel."

Castiel could only stare in disbelief, his worst fears realized. "You." He still didn't want to believe it.

Uriel shrugged one shoulder. "I'm afraid so."

"And you broke the devil's trap, set Alastair on Dean," Castiel accused.

"Alastair should never have been taken alive," Uriel retorted. "Really inconvenient, Cas."

Castiel internally flinched at the stone-cold declaration, and the use of Dean Winchester's nickname for him. Coming from Uriel, it sounded derisive.

"Yes, I did turn the screw a little," Uriel went on. "Alastair should have killed Dean and escaped, and you should have gone on happily scapegoating the demons."

"For the murders of our kin?" Castiel asked incredulously. He couldn't bear to hear this any longer, and yet he couldn't stop the flood now that he'd opened the gates. There were so many things Uriel had done that could not be forgiven, but among them was he had almost made Castiel complicit in Dean's death.

"Not murders, Castiel. No. My work is conversion. How long have we waited here? How long have we played this game by rules that make no sense?"

"It is our father's world, Uriel," Castiel pressed. Who was this angel, this brother, standing before him? When had Uriel become a zealot?

When had Anna become a blasphemy? And why hadn't Castiel seen either coming?

"Our father?" Uriel spat. "He stopped being that, if he ever was, the moment he created them. Humanity, his favorites. This whining, puking larva."

Castiel bristled. "Are you trying to convert me?" Because this was not an argument to succeed in that; Uriel should know better.

"I wanted you to join me," Uriel admitted. "And I still do. With you, we can be powerful enough to—"

"To?" Castiel interrupted, a chill running through his veins. There was still a thread of denial, if he could just keep from hearing Uriel's next words.

"To raise our brother."

"Lucifer." Castiel felt an invisible vice closing around his chest. So this was it. Uriel had betrayed them, betrayed Heaven.

"You do remember him?" Uriel cajoled. "How strong he was? How beautiful? And he didn't bow to humanity. He was punished for defending us. Now, if you want to believe in something, Cas, believe in him."

"Lucifer is not God," he rejoined sharply.

"God isn't God anymore. He doesn't care what we do. I am proof of that."

No, Castiel refused to believe it. Uriel had deceived their superiors, and God…there had to be a reason. Sam had come in time to save Dean from Alastair. But Dean was barely hanging on somewhere in a hospital… Why?

Castiel drew his shoulders back. "What were you gonna do, Uriel? Were you gonna kill the whole garrison?"

Uriel shook his head almost sadly. "I only killed the ones who said no. Others have joined me, Cas."

And that was a terrifying thought. How could he know who had been approached and turned, and who had simply not yet been targeted?

"Now, please, brother," Uriel coaxed, "don't fight me. Help me. Help me spread the word. Help me bring on the Apocalypse."

Castiel felt his heart cracking into pieces. So much death, so much waste. The members of his garrison, his brothers and sisters…Dean…

"All you have to do," Uriel continued, "is be unafraid."

Castiel gazed at the floor. Emotions he was unaccustomed to experiencing all at once roiled inside him like a gathering storm. He knew he had to put them aside and not let them become the weakness his superiors feared they would be. And yet, despite the maelstrom of horror, shock, indignation, and anger, Castiel felt these emotions coalescing into a kind of strength he'd never before possessed. And fear was not part of it.

"For the first time in a long time…" he said quietly, and lifted his head. "I am."

Uriel smiled in victory. Castiel pulled his arm back and punched the angel in the chest with enough force that he went flying backward through a brick wall as though it were plaster. With a grunt, Uriel got to his feet, angel blade still in hand. He wobbled slightly as he stepped back into the room, lip curling upward around a thin trickle of blood.

Castiel didn't have time to draw his own weapon before Uriel attacked. He managed to throw one arm up to block the blade thrust toward his shoulder, but that left him open for Uriel to land a punch to his jaw. Castiel retaliated, and they each exchanged several more blows.

Then Uriel grabbed him by his coat and flung him around. Castiel crashed through a metal support beam, snapping it in half. The impact dazed him, yet he rolled instantly to his feet to face Uriel again. His steps were slightly unbalanced, and he spat a glob of blood from his mouth, but now had the opening to draw his angel blade as well.

Uriel sneered and lunged. Celestial alloy clashed in a screeching collision, the blades sliding down to the hilts. Castiel wrenched away and threw a punch at Uriel's cheek, snapping the angel's head back with a crack. He followed through with a slice across Uriel's bicep that scored a blazing blue gash through his suit.

Uriel let out a vicious snarl and delivered a right hook that sent stars across Castiel's vision. He saw an appendage come swinging toward him, and raised his arm to block. But it left his side exposed, and a split second later, fiery hot pain exploded between Castiel's ribs. His muscles seized in shock until he felt the blade pulled from his flesh. Bright blue light poured out, and Castiel dropped to his knees.

Swaying where he knelt, Castiel looked up as Uriel stood over him. "You can't win, Uriel."

The other angel kicked Castiel's blade out of his hand, then reached down to clamp a hand on his shoulder, bracing him in a pantomime of camaraderie.

Castiel's breath hitched, and he tasted copper in the back of his throat. But if this was to be his end, he would face it as an angel of the Lord. "I still serve God."

Uriel's face was twisted with rage, blood streaming from several cuts. "You haven't even met the man!" He tightened his grip on Castiel. "There is no will." Uriel punctuated his statement by slamming the pommel of his blade into Castiel's face. "No wrath." Then again.

Castiel grunted under the punishing blows.

"No God." Uriel raised his fist again, this time angling the tip of his blade downward, but before he could strike, Anna suddenly appeared behind him, and stabbed an angel blade through his neck.

Castiel stared in utter bewilderment.

"Maybe." Anna leaned in toward Uriel's ear, her voice a low rasp of vitriolic hatred. "Or maybe not. But there's. Still. Me."

She wrenched the blade out, and Uriel gurgled as he dropped to the floor. Anna came to stand by Castiel, though he was still too dazed to say anything. Uriel's mouth flew open with a cry as light blazed forth, then exploded from him in a concussive force. When the supernova had faded, the scorch marks of wings were seared into the floor around his empty vessel.

Castiel lolled his head up to gaze in wonderment at his rescuer. Anna, the sister he loved. The captain who'd left him alone and betrayed and doubting when she'd left Heaven, when she'd committed blasphemy by ripping out the grace of God from her essence. The one who'd begged him to see through the lie of revelation and stop Dean before things with Alastair went too far.

Castiel had failed her. He'd failed Dean. He didn't know what was right or wrong anymore. What did he do when following orders was the morally wrong action, but doing what was right went against the command of Heaven? Where was the line between being a good soldier and straying down the same path Uriel had?

The room was spinning darkly, and Castiel felt as though the floor was crumbling beneath him.

"Anna…" he gasped, not wanting to fall. He still didn't want to fall… Not when there was no one there to keep him from the abyss.

It claimed him anyway.

Anna dropped to her knees just as Castiel's eyes rolled back and he slumped to the side. She caught him before he hit the filthy floor, and cradled his head against her shoulder. The stab wound in his side was still leaking grace. She felt a thrill of fear for him then; the injury was grave and needed attention, but she couldn't take him back to Heaven, nor could she leave him like this with Uriel's body for another of the garrison to find. There was too great a risk that it would be someone who had defected.

Tightening her arms around Castiel, Anna gave a tremendous flap of her wings. They landed in a vacant cabin far away, and she gently eased him onto the bed in the corner. It was still night out in this time zone, and Castiel's oozing grace cast a dull glow throughout the room. She quickly knelt beside him and pressed her palm against the wound. The heat of blood pulsed against her flesh, the vessel's life force ebbing and flowing along with the angelic essence that had also been injured.

Anna's throat constricted. Cut off from Heaven as she was, she didn't have the power to heal. Which meant she'd have to take a more mundane approach. First, she needed something to make bandages with. She stood and strode over to the nearest cabinets and began rifling through their contents, not caring about throwing what she didn't need aside. The owners of this place would have a large mess to clean up when they returned, but that was of little concern to her.

She eventually found a first-aid kit stocked with large rolls of gauze, and hurried back to Castiel with it. The stab wound in his side had bled more, spilling red down to stain a small spot on the bedcover. Anna ripped open a square patch of gauze and pressed it against the wound hard, trying to staunch the flow of life energy. With her other hand, she began unrolling the longer wraps. Getting it under Castiel so she could wrap it all the way around his torso was difficult, but she managed. She taped the ends in place and rocked back to study her work. It would hold the vessel together, at least, while Castiel's grace fought to heal his true form.

She turned her attention to the brutal abrasions and bruises on his face. There was little to be done in terms of bandaging those, but they needed to be cleaned. Getting up again, Anna went in search of water, and found a gallon jug in the storage closet. She opened another patch of square gauze, got it wet, and proceeded to wipe the blood from Castiel's face. The split skin stood out starkly in the wan starlight that filtered through the windows, if only because Anna could see how it reflected the state of Castiel's grace underneath.

Her chest tightened. If only she had checked on him sooner. But she'd still been sore after their last conversation, and had decided to let Castiel stew in his doubt a little longer. She had no idea Uriel was to blame for the angel murders, though she'd suspected it couldn't have been demons. But she also hadn't expected Castiel to confront Uriel; in truth, Anna thought he would have buried his head in the sand again. She'd forgotten just how stubborn and persistent Castiel could be. This wasn't even the first time he'd been injured in battle and she'd sat vigil by his side.

They were pinned down. Lucifer's Knights of Hell had lured the garrison into an ambush and they'd been separated. Anna herself had sustained minor injuries, her grace dribbling out like stardust down her sword arm. Balthazar's wing had been dislocated, leaving him grounded in a small trench she and Castiel had taken a defensive position in. But they wouldn't be able to hold it.

Inias and Hester were in a similar strait several yards off. Anna had no idea where the rest under her command were, if they were also trapped somewhere in this forsaken forest, if they'd retreated, or if they'd been dragged through the nearby portal into Hell.

Balthazar cried out as Castiel pushed the wing joint back into place. He still wouldn't be able to fly out of here.

Anna mentally ran through their options, but unfortunately, all she was coming up with was fighting and dying with honor in the name of the Lord. By the frightened yet staunch looks on her soldiers' faces, they knew it, too.

"More are coming through the portal," Balthazar said, voice heavy with pain.

Anna let out a noise of frustration. Where were their reinforcements?

Castiel suddenly straightened. "We need to close it."

Balthazar scowled. "Good thinking, genius." Physical agony was doing nothing to blunt his abrasiveness.

Castiel seemed unaffected by it, however. "We just need to destroy the sigils."

"The portal is surrounded by Knights," Anna pointed out, unable to keep her own irritation from her tone. Not at Castiel, of course, but at their eminent failure and demise.

Castiel squared his shoulders. "I just need to be fast enough."

Balthazar's eyes widened, and Anna whipped around, but it was too late, Castiel had flown from their cover and was racing across the terrain.

"Castiel, no!"

She watched in horror as he dodged through the demons, not even bothering to meet their attacks. He had a single-minded purpose—reaching that Hell portal. A hulking Knight stepped into Castiel's path, but he ducked under it and kept going. Several demons had turned to chase him down. Even if he closed the portal, there was no way he'd fight his way back. Anna tightened her grip on her angel blade in preparation to fly to his aid, but she hesitated, unwilling to leave Balthazar vulnerable either.

Castiel reached the portal and struck the demon guard across the face. The sigils powering the portal were exposed. And the demons were closing in.

The air crackled for a split second as Castiel summoned the power of Heaven and exploded his grace outward in a massive smiting. The concussive force whomped in Anna's ears, and several horrendous screams rent the air. She felt the pressure shift, and when Castiel's supernova attack faded, she saw the portal collapsing in on itself, taking several of the Knights with it.

But not all of them.

Anna was up and out of the trench in an instant, even though she knew she'd never make it. Castiel parried a blow, then a second, but he was soon swarmed with demons, and a massive smiting like that against superior Knights and a portal had left him drained. His back arched as a blade was thrust through his torso. Another Knight came up and stabbed him a second time, while a third lesser demon descended on his wings. Castiel's screams tore through the forest, shaking the trees.

Anna threw herself at the nearest Knight, ramming her angel blade through his throat. She didn't stop to see if it had killed him before yanking the sword out and spinning toward the second. It wrenched its own weapon from Castiel in time to block her strike, silvery blood streaming down its reddish blade. Anna attacked with fury, driving the Knight back against a rock face where she managed to deliver a blow through its chest. His mouth flew open, orange light spritzing out as he crumpled. There was a chance he'd survive the wound; Knights were notoriously hard to kill, but Anna didn't care. She whirled around. The third demon, seeing its superior companions defeated, took off like a coward.

Anna dropped to her knees next to Castiel, who lay in a broken, bleeding heap on the forest floor. "No." She scooped an arm behind his back and lifted him up to lean against her. His grace sputtered, leaking from several wounds. Castiel's eyes were closed, expression horrifyingly slack.

Uriel appeared in a flutter of wing beats. "Anna, thank goodness you're alive. We tried to reach you, but there were too many—"

"Get a Rit Zien!" she snapped.

Uriel bit back a response, but then gave a clipped nod and flew away.

Balthazar limped toward them, eyes downcast and expression grieved. He didn't say anything, and neither did she.

The Rit Zien responded quicker than the calvary, which Anna would wonder about later. At the moment, all she cared about was the angel fading in her arms.

"He is gravely wounded," the medic said solemnly after looking Castiel over. "Perhaps it might be best…"

"Don't you dare." Anna shot him a scathing glare. "He'll make it."

The Rit Zien gave her a compassionate look. "He might not. And it will take time."

Anna glanced back at Castiel and tightened her arms around him. "He's strong enough."

Anna felt moisture prickling at the corners of her eyes as she remembered. It had been touch and go there for a while. She and Balthazar had taken turns watching over Castiel, praying at his bedside for him to heal.

And he had. The stupid, brave idiot had saved them because he didn't know when to back down from a seven-headed dragon. So of course he wouldn't have thought twice about confronting Uriel alone. And Anna never would have forgiven herself if she'd gotten there too late and Uriel had killed Castiel.

She brushed some hair away from his face. He was strong. He'd survive this, too. The physical injuries, and the emotional ones he was bound to experience when he woke up. Strange, how embracing emotions was what she had been nudging him toward, and now she would give anything for him not to feel the sting of betrayal and shattering of faith. Castiel and Uriel had been friends, after all.

His face scrunched up, and a low moan rumbled in his throat.

Anna straightened and took his hand to squeeze it. "Castiel? Open your eyes."

"Anna?" he rasped, chest hitching.

"Shh, don't try to move yet."

His eyelids sluggishly dragged open to stare at her. "You came back."

"Yes."

Almost too late, but yes.

"You killed Uriel."

She tensed, braced for accusation. She didn't detect it, though, just a dully delivered statement of fact. "He was trying to kill you," she said.

"He was working against us."

A stitch in her chest began to loosen. Us. "Yes."

Castiel closed his eyes as though to hide the swell of grief, but she felt it wafting from him like a cloying perfume. "I'm sorry," he said in a low voice. "I failed to see it. You tried to tell me…"

"I didn't know it was Uriel." She took a deep breath; she wasn't sure Castiel was in any state to resume this argument, but the urgency of everything waiting for them outside this cabin seemed to be pressing in upon them. "Castiel, the orders for Dean to torture Alastair, those weren't Uriel's. There is still something wrong in Heaven."

His eyes snapped open to glare at her in recrimination. "What you're asking me to do…"

"Is to think for yourself," she replied sharply, then reached out to stroke his hair back in an effort to soften her demeanor. He was still vulnerable, and she couldn't push him, not in the way he wanted.

"I'm asking you to question, to evaluate whether you are truly doing God's will just because some unknown angel upstairs is ordering you to."

"But…"

"I understand what you're going through." Anna sighed. "And I unfortunately can't make it easier. This is something you have to decide for yourself. Just…" She squeezed his hand again. "I will be here, Castiel, should you choose the right path."

He shook his head in denial. "The right path…disobedience…how can those be the same?"

"You're not disobeying God," she insisted.

Castiel's pained gaze drifted toward the ceiling and beyond. "Why won't He tell me, then?"

She didn't have an answer for that.

"Just rest right now, Castiel. Regain your strength."

He struggled to sit up, only to collapse back with a grimace. "The Seals, the war…there's no time. And if what you say about Heaven is true…"

"We'll figure it out," she assured him. "Shh, Castiel. Please rest."

He didn't require much coaxing, as exhaustion was already pulling him under again. "I need to check on Dean," he murmured quietly. "He's my charge."

Anna stroked his hair. "When you're stronger, I will take you to see him," she promised.

Castiel drifted off. The bruises on his face had yet to fade, and the bandage around his torso had a patch of red seeping through. He still needed time to heal.

Anna leaned back in her chair to watch over him. Castiel was strong, she knew that. But she worried about what the coming war would do to him.

What it would do to all of them.