A/N: Sorry for the delay, but it's the holidays!

Four

Something was chasing her—some monster. She ran through the trees, stumbling over roots and rocks. Where was Castiel? Hadn't he been right there? The creature was closing in on her. She could hear its ragged breath right behind her. She took a running leap down the side of a hill, lost her footing and tumbled head-long into the ground. It followed.

Panting hard, ignoring the pain in her body, she flipped over onto her back, her angel blade in her hand, yelling as the creature landed on top of her—

"Brooke!"

She came awake with a yell, half-blind, struggling with whoever—whatever—was grasping her arms.

"Brooke!" he repeated.

"GET OFF!" she screamed, feeling for the angel blade she kept under her pillow.

Whoever was there let go of her, and she lunged after them, but something in her own body was preventing her from killing whoever it was. Her muscles fought against her, screaming in disagreement. She came fully awake with the pain in her body, and saw herself, holding the blade a half-inch from Castiel's left eyeball. She stared at him, trembling, then threw the blade far away, across the motel room. It had been Castiel's Grace, in her body, that had stopped her from stabbing him.

Panting, she said, "I—I'm sorry."

"It's all right," he said, keeping his hands up in an 'I surrender' fashion.

"No. I almost stabbed you. I could have killed you, I… Could I have killed you, stabbing you in the eye?" She didn't know why she had latched onto that question, but it was already spoken.

"I don't know," he replied. "Maybe. Probably. It's a long blade. Would've pierced my brain, at some point."

"Oh, God," Brooke said, and put her face in her hands. "I almost fucking killed you."

Castiel's voice was surprisingly calm, given the situation. "I should have known better than to touch you while you were like that. I only meant to wake you out of your nightmare, but…"

She heaved a sigh and fell against his chest, trembling, breathing shakily, trying to pull herself together. "I thought… I thought I wasn't scared anymore," she whispered. But, it seemed, her brain had other plans.

Castiel said nothing; he simply tangled his fingers through her hair, and let her breathe.

###

They—Brooke, really—had breakfast in some little diner somewhere, and she relished her omelette and hash browns. And coffee. She loved coffee. Like most Hunters, she was probably addicted to the stuff, since late nights and early mornings were the standard in her line of work.

Castiel stared at her she brought the mug to her lips. She swallowed some of it and said, "What?"

He tilted his head. "Can I… try it?"

She smiled in amusement and held out the mug to him. "You hate food; I don't imagine you'll like coffee. It's bitter."

He took the proffered mug and drank some of the coffee, immediately making a face. Smacking his lips and shaking his head, he handed the mug back to her. "Why does anyone drink that?"

She laughed. "To stay awake, mostly."

After breakfast, Castiel teleported them off to see Sam and Dean, who were at an auto repair place that was also a gas station. Castiel stood, leaning against the Impala, reading the newspaper. In his suit and tie, trench coat over top, reading like that, he looked almost human, and Brooke smiled at him. Except that she could see the angel underneath.

"What's the word, Cass?" Dean asked, coming over to the two of them.

"It's a shortened version of my name," the angel said.

Brooke laughed. "That's not…" she began, and then shook her head and gave up. There he had been, looking so human—and he had to go and ruin it by reminding them all of how much of an angel he really was.

Dean glanced at her, then looked at Castiel. "Yes, it is," he said. "I meant, what's the word on the Word? Any, uh, tablet chatter on angel radio?"

Castiel glanced up from the paper. "Oh, I couldn't say. I turned that off."

"You can do that?" Sam asked.

"Yeah, it's a simple matter of blocking out certain subsonic frequencies. I could draw you a diagram if you want."

"No—that's—we're good," said Dean, sounding like the last thing he wanted on Earth was to stare at some nonsensical diagram of how angel telepathy worked.

"I want a diagram," Brooke said, interrupting whatever he'd been about to say next.

Castiel looked at her.

"Well, you communicate with me telepathically all the time," she said. "But you haven't blocked me out, which means our connection can't be the same frequency as the angels. Or whatever."

Castiel bent down and stuck his head through the window of the Impala, pulling the glovebox open. He straightened back up after a moment, with a pen in his hand, and began to draw on the newspaper, in large, bold strokes.

"Why'd you flip the switch?" Dean asked.

Castiel's eyes concentrated on what he was drawing, but he said to Dean, "Because it's a direct link to Heaven. And I don't want anything to do with that place—not anymore."

Brooke studied the side of his face, and listened to the background thoughts in his mind. He was sad about a lot of things, but there was a glimmer of hope in all that darkness, too.

Castiel looked up from drawing on the newspaper and handed it to her. He had drawn heavily, so that she could see the diagram over top of the print. Quietly, he stood, looking over her shoulder, pointing with one finger, explaining each line, each section. His voice was calm and warm in her ear; he was so close as to be nearly touching her, and heat radiated from him, warming her right side. Brooke couldn't say, at the end of a minute, that she really understood everything he had just shown her, but she thought she got the gist of it.

"Basically you're just sending out a separate frequency that acts like a radio jammer?" she asked. "The same frequency as the one you receive, so it… messes it up, right?"

"That's correct," he said.

"Humans run at a separate frequency from angels, so if I wanted to block you from my mind, I'd send out a different frequency from the one I use to block out angel radio."

"So it's… less magic, more science," she murmured, staring down at the drawing.

"It's both. I need magic to be able to send the frequency, but from there it becomes science."

"Hey!"

Dean's voice startled Brooke. She flinched and stared up at him. He was looking at the two of them like they were crazy. "Shut up, nerds," he said.

She laughed, then turned to face Castiel and kissed him on the cheek, before flouncing around to the other side of the Impala to show Sam the diagram. His face, earlier, had indicated an interest in seeing it. He took it from her and studied it, as Dean spoke to Castiel.

The next thing that she truly heard Castiel say was, "I'm gonna become a Hunter."

"You what?" she asked, staring at him over the top of the Impala. But he was smiling so joyfully that she couldn't even maintain her surprise. All she could do was smile back.

Sam laughed at Castiel. "Really?" he said.

"Yeah. I could be your third wheel."

Brooke squeezed her eyes shut, trying not to laugh. "Cass, that's—that doesn't mean…"

"You know that's not a good thing, right?" Dean asked, finishing what she had been trying to say.

"Of course it is," said Castiel, happily "A third wheel adds extra grip, greater stability—

"So what am I, then?" Brooke asked, her hands on her hips.

He smiled at her again. "You'd be the fourth wheel, of course."

Brooke lost her shit, and bent over with her hands on her knees, dying of laughter.

"Don't laugh," said Castiel, sounding a little crestfallen. "I even found a case…"

"No, I'm not…" Brooke began, and sucked in a few breaths, before standing up straight again. She stared at him. "Castiel, I love you. I would never laugh at you… Okay, I would laugh at you, but remember what I said about family and teasing you?"

"Yes," he said, nodding. "You told me that family teases you because they love you."

"That's right," she said.

He nodded again. "Right. The case." He motioned for Sam to hand him back the newspaper, and took it from his hand, then turned and gave it to Dean. "Oklahoma City—a man's heart jumped ten feet out of his chest. It sounds like our kind of thing, right?"

Our kind of thing.

Our, because Castiel wanted nothing more than acceptance into the group. To be part of the team.

Brooke continued to smile at the angel, over the top of the Impala, but she was beginning to see and feel the cracks in his cheery demeanor.

Since entering Purgatory, Castiel's insanity from absorbing Sam's "cage match scars," as Dean called them, had disappeared. It was as if going to Purgatory had been what he wanted all along. He had accepted his punishment for his hubris, for releasing Leviathans onto the Earth, for mass-murdering so many angels up in Heaven, for causing Sam's insanity. Being there had steadied him, strangely.

The one to go insane from being in Purgatory had been Brooke. All Hunters had PTSD; it came with the job. But the longer she had been in that monster-infested place, the worse it had all gotten. And Castiel had, once again, become her rock. And when they had reappeared on Earth, he had kept up that strength, for her, as she was now suffering the after-effects of being in a constant state of fight-or-flight for a year. Her nerves were shot; her temper was short; all she wanted to do was sleep, but when she fell asleep, her nightmares were so vivid that it became difficult to tell what was real anymore.

So, Castiel remained strong, for her. Outwardly, anyway. But he could not hide himself from her, for she knew his mind. His heart. And he still felt just as guilty as ever—now doubly so, since he blamed himself for her current PTSD, despite the fact that she had chosen to stay with him in Purgatory when she could have left a little earlier with Dean. He still craved the love and acceptance of these two men—Dean, especially. He still felt that he had not served enough penance, that whoever or whatever had lifted him from Purgatory had done so too early. Now, he smiled up into Dean's face to hide all that pain, that guilt.

He was strong for her, and claimed himself to be stronger than Dean for staying in Purgatory. But the truth was that he wanted nothing more than to prostrate himself before Sam and Dean, before Brooke, and cry, and scream, and beg for forgiveness. He was just as broken as she was. And they were the only two beings in the world who could possibly hold each other together, because they were the only two beings in the world who could possibly understand—truly understand.

Brooke moved silently around the side of the Impala, to her husband's side, and held his hand, feeling, suddenly, exhausted.

###

Brooke stood in the background of the room, observing Castiel as he tried to play "detective" with Sam and Dean. Detective Glass, the woman who was offering information on this case, had been off-put by the presence of four FBI agents, but they'd been prepared for that. The story was that Sam and Dean (obviously using different names) were the true agents on the case; Castiel was in training to become an agent, and Brooke was there to observe him.

Castiel's problem was that he was… a little too eager to please, and had ignored any advice that she had given so far.

After Detective Glass left the autopsy room, Castiel bent down over the corpse of the man whose heart had leapt out of his chest, and smelled him.

"What are you doing?" Brooke asked, but her voice was tired and she didn't really care to try and stop him, at this point. Everyone left in the room was used to his odd behavior, and he wouldn't listen to her, anyways.

"Mr. Frieling's arterial health is, uh, excellent," said Castiel. That was when he bent down over the body and sniffed at it. "Mm," he said, his mind spinning as he tried to put something together. "He did recently suffer from a… mild, uh… what is that? Bladder infection." He stood up again, looking exceedingly proud of himself.

Dean stared across the room, at Brooke.

Brooke stared back, with a shake of her head and a small shrug of her shoulders, like, I don't even know, man.

Dean sighed, pinched the bridge of his nose between his fingers, and then looked at the angel. "Cass," he said, "stop smelling the dead guy."

"Why?" Castiel asked, immediately.

Brooke snorted in amusement and closed her eyes. He was like a child. She could feel his slight irritation at her laughter, but he ignored her.

"Now I know everything about this man," he continued. "So, we can—

"Did you know he was having an affair?" Sam piped up, reading the file that Detective Glass had given him.

Castiel stared at him. "What?"

Dean glanced at Brooke again, smirking, and landed his gaze on the angel. "Strike one, Sherlock," he said.

You should know by now, Cass, Brooke said, silently.

He turned to look at her. Know what?

She shook her head at him with an amused smile. That most of the stuff you need to know about a person isn't in the body. She tapped her head, then pointed to his. It's in the mind. The heart.

Castiel stared at her.

Would you have been able to tell, just by looking at me, that you'd be married to me, one day? she asked.

He smiled a little, seeming to finally understand. No, he said.

###

Brooke stood, once again, in the background, observing Castiel as he went about pretending to be an FBI agent. Now they were at the dead guy's house, talking to his wife. And everything was going well—until Castiel absolutely lost his shit.

"Now, Ms. Frieling," Castiel said to the woman, leaning down over the table she was sitting at.

Cass, what the fuck are you doing? Brooke asked, sensing something building in him.

He ignored her. "I don't want to bother you," he said. "I-I really don't. But I-I do have just one question for you…" He slammed his down onto the table—Brooke's mind shattered into a thousand pieces as her husband did something violent and loud five feet from her—"WHY DID YOU KILL YOUR HUSBAND?"

Holy fucking shit.

"Agent!" Brooke snapped, loudly, angrily, while trying to keep herself from going off the deep end.

Castiel turned to look at her.

"Agent Stills, a word," Dean broke in.

Castiel kept his eyes on Brooke's face for a moment, beginning to realize what slamming his hand down on a table and yelling might do to someone suffering from PTSD. But Dean was gesturing angrily with his eyes for him to go over in the corner with him.

The angel followed Dean like a kicked puppy. "What?" he whispered. "I was being Bad Cop."

"You were being bad everything," Dean snapped.

"Please," said Sam, sitting down across the table from the poor woman who had just been traumatized by Castiel's utter stupidity. "Forgive my partner. He's, uh… he's going through some stuff."

Castiel, sufficiently lectured, glanced at Brooke out of the corner of his eye.

I swear to God, Cass… she said. Think before you do shit. Brooke was still trembling from the sound of him slamming his hand down on the table, from the sound of him yelling. It had not been directed at her, but it had shocked her system to hear it.

###

Later, after finding out about another death—a man who hovered in the air after stepping off a building before falling—they all went back their motel rooms.

Brooke sat alone in hers. Castiel had all but completely avoided her since causing her so much trouble earlier in the day. She sat on the edge of the bed, rubbing her temples with her fingers, wondering if she should have come with the three of them at all. Wondering if, maybe, she didn't have what it took to be a Hunter anymore. What if they caught up to whatever monster was causing these deaths and she froze? That was how Hunters were killed—when they stopped having the guts to do the job.

She stood up and began to pace the room, worry overwhelming her.

Castiel, next door in Sam and Dean's room, tethered to her mind, could feel her slipping. He appeared in the room, suddenly.

Brooke felt the wind at her back and turned to face the angel. "I can't do this, Cass," she said.

"You can," he replied.

"No." She shook her head. "I'm gonna get someone killed, going after this monster. Or any monster. I—I'm not fit—

Castiel took two long strides toward her and touched her face. "You are strong," he said, and he sounded so sure.

"Strong, sure," she whispered. "But I'm just as broken as you are. No offense. Just… in the opposite direction." She sighed. "We came back from Purgatory and the first thing you wanted to do was find Dean and stick to him like glue, become his… pet. Beg for affection and forgiveness." She turned away from Castiel and rubbed her arms. "The first thing I wanted to do was die. Curl up on the floor and never get up again."

Castiel was silent for a long time. She could feel his mind working, trying to rationalize what she had just said to him. Trying not to take that jab about being Dean Winchester's pet personally.

"I'm sorry I frightened you," he finally murmured.

"What the hell were you thinking?" she snapped, spinning around to face him again. "Look, you let Sam and Dean do the talking, okay? You're a fucking idiot, apparently. We don't need you scaring the shit out of anyone else."

He stared at her, sadly, his eyes mirroring betrayal, shock.

Brooke swallowed, looking away from him. "I'm sorry," she muttered. "You shouldn't let me talk to you like that."

"It's… fine," he said, even though it wasn't.

"I just don't get it," she said, quickly, not ready to deal with whatever tension was building between the two of them. "Facing off against Crowley, I was fine, even when you were loud. Even when you smashed into that glass table." She shook her head. "But then you do something so… mundane. Without even using your powers. Slam your hand down on a table and yell. And… I couldn't deal with it. Suddenly, you were too loud." She was shaking. "It's like my symptoms come and go, at random. I'm fine and then I'm just… not."

And she realized that talking about this was just making the tension worse. She could hear Castiel's Grace in her mind, in her ears, ringing like tinnitus, loud and whining. But it was coming from the Grace in her body. She squeezed her hands into fists, trying to breathe slowly, trying to force the Grace back down.

Castiel stood like a statue behind her, but she could feel him there. Worry exuded from him in waves.

"I don't want to fight anymore," she whispered. "But I want to fucking kill something." The Grace in her blood rose higher, roaring in her ears. Her eyes went white as it overpowered her, each pulsation coming faster until they ran together in one, long scream. Inside the white of her vision, all she could see was every monster she had killed in Purgatory. Every chase. Every time one of them hurt her. Every time she bled, or made something else bleed.

When she finally came down from the high of Castiel's Grace, she realized he was holding her. She was shaking uncontrollably, shaking so hard that her teeth were chattering. She clenched her jaws together to stop the noise. She dug her nails into her hands.

In her head, she heard a different noise now, one that Castiel was hearing. It was… police chatter?

"Sorry," Castiel murmured, pressing his fingers to his temple. "It's… There's been another death."

"Go," Brooke said, stepping away from him.

"Go?"

"With Sam and Dean. To check it out."

Castiel gazed at her, concern and sorrow and love all pouring from him at once. "No, I—I don't think you should be left alone right now," he said.

"I'm a big girl," Brooke said, folding her arms over her chest and turning away from him. "Go."

"Brooke—

"Please!" She closed her eyes. "Please, just go."

There was a moment's pause, and then she heard the sound of his wings unfurling, and felt the wind on her back as he teleported from the room.