Cass had been staring at her notes for a few hours straight, and a headache had started to build behind her eyes by the time Sam knocked lightly on the doorframe of her bedroom. Cass looked up at him curiously.

"Hey." Sam raked his eyes over all the papers spread out across her bed. "Hope I'm not interrupting."

"I could use an interruption," Cass said honestly, closing her laptop. "What's up?"

"I'm about to do a grocery run, and I thought I'd ask if you want to come," Sam explained, "There's not exactly a lot of vegetarian stuff on Bobby's shopping list, and I thought you might be getting tired of canned soup and cheese sandwiches..."

Cass smiled. She wasn't going to complain aloud about canned soup and cheese sandwiches while she was living on Bobby's hospitality, but she wasn't going to turn down an opportunity for some real food, either.

"I'd like that."

Twenty minutes later, Cass was walking through a grocery store with Sam Winchester, checking avocados for ripeness and comparing different brands of pasta. It was an incredibly normal and domestic thing to do, which just made it all the more weird, because she was doing the normal, domestic thing with Sam Winchester. Those sorts of thoughts were becoming less and less frequent over time, as Cass got used to thinking of Sam less as a character and more as a person, but they still happened.

She was finding it easier to separate the Sam Winchester she was getting to know from the character she'd been familiar with than it was to separate the two for Dean, or Bobby. She supposed it was because her interference hadn't changed much for either of them. Sure, Dean had spent less time in Hell, but he'd still been there. The Sam Winchester adding carrots and lettuce to their shared shopping cart, meanwhile, was quite different from the character she'd known already. He'd never drank Ruby's blood, never unleashed the Apocalypse. He was missing a darkness to him, a guilt, that he otherwise would have carried around for the rest of his life. And now he never would, because of her.

She wasn't sure how she felt about that.

"How long have you been vegetarian?" Sam asked as she piled several packages of tofu into the cart. "If you don't mind my asking."

"Let me think. I started when I was 18, so…" Cass performed some quick mental math. "Nine years."

"You're 27?" Sam looked surprised.

"Why," Cass teased, "do I look older?"

"No," Sam said quickly. "No, I just—I didn't realize you were older than me."

Cass's lips twisted with dark humor. "If it makes you feel any better, 'older' is subjective."

Sam furrowed his brow. "What's that supposed to mean?"

"What year were you born?" Cass couldn't remember off the top of her head. She knew it was in the '80s, but didn't know the year.

"'83," Sam said, still looking confused.

Cass tapped her once chest and said, "'92."

"Wait, what?" Sam stopped walking, voice rising with disbelief. "Then you should be, like, 16."

"I was, in 2008," Cass said. "Remember when I said the show ran for like 15 seasons? This is only season 4. No, not even that—this is still the break after season 3."

"But, wait. If you were 16 in 2008, and you're 27 now, then you're from…" Sam started to do the math in his head. Cass saved him the trouble.

"2020."

"Seriously?" Cass nodded. Sam shook his head, amazed, then asked, "What's it like?"

Cass sighed, trying to think of a way to answer that question. "It's… one for the history books."

Sam furrowed his brow again. "What does that mean?"

Cass glanced around to make sure none of the other shoppers were listening, then told him, "My universe might not have monsters, but it does have a global pandemic. Also, high-waisted jeans have also made a huge comeback and Donald Trump is the president of the United States."

Sam opened his mouth. Hesitated. Thought for a bit. "You know? I think I prefer the monsters."

Cass huffed a laugh at that, and Sam smiled back at her, relieved that she hadn't taken offense. They finished the shopping quickly after that, and soon enough they were piling the grocery bags into the trunk of the Impala. A good third of the space was taken up with beer, and half of the remaining space was taken up with canned goods, shelf-stable foods, and meats both fresh and frozen, but Cass had fresh vegetables and vegetarian proteins for the first time in weeks, so she was content.

Or at least, she was, until she turned to take one of the last bags from the cart and saw Uriel walking slowly towards them across the parking lot.

Cass froze. The bag she'd been picking up fell, sending oranges rolling across the asphalt.

"Woah." Sam looked at the oranges, then to Cass, concerned. "You okay?"

Cass didn't answer. She couldn't answer. She was too shocked, and afraid, and overall, confused. Uriel shouldn't be here. There was no reason for him to be here. He'd been exposed. He should be in Hell. Had he changed his mind about hurting her? Had he decided that, if he was going to rebel against Heaven and work for Lucifer, that murdering a Prophet wasn't forbidden, after all? Or was he just willing to risk the wrath of the Archangels for revenge?

When Cass didn't speak, Sam followed her gaze. He stiffened.

"Uriel," he said, darkly. "What are you doing here?"

The angel was only a dozen feet away now. He didn't have a weapon drawn, but that didn't mean he was unarmed. Uriel answered Sam evenly. "Righting that which has gone wrong."

In one motion, Sam stepped in front of Cass and pulled a wicked-looking knife out of his jacket. He held the blade in a defensive stance and said firmly, "Get back."

Cass ought to be doing something. She ought to be drawing a sigil, or praying, or something aside from standing like a deer in headlights, but she didn't have a knife on her to draw blood for a sigil, and she couldn't think.

Uriel smiled his unkind smile. Six feet away, now. "I'm not here for the Prophet."

Cass didn't like the way he said that. She didn't like the way he said that at all. It gave her the push she needed to give up her imitation of a statue, and she quickly pulled Sam behind her by his shirt, maneuvering herself between him and Uriel and doing her best not to cut her face open on the knife Sam was still brandishing.

"Cass?" She didn't know if Sam was trying to ask her what she was doing, or what Uriel was doing, or both. She didn't really have any answers for him either way. But she did know one thing, from Uriel's words and the way his dark eyes glittered, not at her, but at Sam.

"He can't touch me, remember?" She said, not turning away from Uriel for a second. She was still pressing Sam backwards, trying to encourage him to back up. "He's not allowed. An Archangel would kill him if he tried. That means he's here for you."

Uriel looked amused. He turned his dark gaze to her, away from Sam, and said with genuine surprise and not a little condescension, "You really think you can stop me?"

No. No, she didn't. She opened her mouth to tell Sam to get in the car and just drive, but it wasn't like Uriel couldn't follow him wherever he went.

"Castiel? A little help?" Cass said, voice high with panic. He hadn't responded to her prayers, but surely if he could hear her now, he would come, right? "Castiel! Oh, fuck it—Michael! Raphael! Is anybody listening?"

Uriel smiled his cold, devil's smile again. "Castiel is busy. And the Archangels won't come. They know I won't harm you." The smile dropped. "Now. Step aside."

Uriel was upon her now, close enough to touch. Sam had retreated further back, but Cass couldn't turn to glance at him, couldn't look away from Uriel. She swallowed hard.

"No."

Uriel did not even blink. He raised a hand to her face, gentle but not kind. "Then sleep."

People were talking to her. She knew they were. She could see their lips moving, could see the concern on their faces, but she couldn't hear them. Not really. She couldn't hear the doctors, or the beeps of medical equipment. She hadn't been able to hear the sirens, either, or the EMTs who'd loaded her and Sam into the ambulance. To Cass, it was all just white noise.

She hadn't heard anything with any clarity since she'd pressed her fingers to Sam's neck and felt no pulse. Since she'd desperately pressed her ear to his chest and heard nothing.

No pulse. No heartbeat.

"I don't understand."

Cass couldn't hear her own voice, so she wasn't sure if she was saying it out loud, or only in her mind. It was the only thought in her head, repeating over and over. She didn't understand why Sam was… was…

"I don't understand."

And then, abruptly, the fog in her mind lifted as she was slammed back against a wall.

"Dean!" That was Bobby's voice, the first sound to cut through the haze. But it was Dean who was holding her against the wall, hands squeezing her shoulders tightly as he shook her. His eyes were livid and bright.

"What the hell happened?" Dean roared at her. "Why is my brother in the morgue?"

Cass shuddered. Tears overflowed from her eyes, and she shut them, not able to meet Dean's accusing stare.

"Dean, lay off her!" Bobby pulled Dean away from her, leaving Cass leaning on the wall for support as she sobbed. "The doctors said she's in shock!"

"I don't care about her feelings, Bobby! My brother is dead!"

Cass sobbed harder, wrapping her arms around herself. With effort, she opened her eyes and looked back at Dean, and then to Bobby. "I don't kn-know," she said, working hard to speak around ragged breaths. "I don't understan-nd."

"What's there to understand?" Dean stepped forward again, eyes wild. Bobby's hand gripping his arm held him back from manhandling her any further, though he, too, was looking at Cass with a look that demanded answers. "My brother just dropped dead without a scratch on him. You were there! What the hell happened? What did you do?!"

"Ur…" Cass shook her head bitterly and forced herself to take deep breaths. "Uriel. He c-came for Sam. I don't know why. I tried c-calling—for angels. For anyone. But no one came." Cass swallowed hard, the movement painful. "I tried… I tried… but he just put me to sleep, and I-I couldn't give him enough time to f… to finish the banishing sigil."

Cass had looked up from Sam's still body when she noticed his fingers were bloody to find the angel-banishing sigil half-finished on the driver's side door, the dark smears barely visible against the Impala's black paint. If she hadn't been so weak, if she hadn't hesitated, if she'd kept her head and thought of something to distract Uriel for just a few seconds longer, then Sam could have finished it.

He could have lived.

"Uriel?" Dean repeated. "The asshole angel, the one working for Lucifer?"

Cass nodded shakily. Bobby frowned. "Why would he kill Sam?"

Cass shook her head slowly. "I don't know. Sam is supposed to break the last seal. He's supposed to be Lucifer's vessel. It didn't make any sense for Uriel to do this. I don't—" Cass scrubbed at her tear-streaked face even as two more tears fell. "I don't understand."

"I do."

The humans in the room all jumped at Castiel's sudden appearance in the hospital room, but Dean recovered almost immediately.

"You." He advanced on Castiel without fear, looming over the angel. "You know why your angel friend killed my brother?"

"Uriel is no longer a friend," Castiel informed him gravely. "And he has taken Sam to Hell in the hopes that you will come for him, and break the first seal."

Dean's face went pale. "What?"

"Uriel and the others, they are still trying to break the first seal and set the Apocalypse in motion," Castiel explained. "They knew they could not simply drag you back to Hell and expect you to shed blood, knowing what you know now. They are counting on you coming to Hell to rescue your brother, and shedding blood in the process."

Castiel turned to Cass then, his blue eyes remorseful. "I heard your prayers. I'm sorry that I could not answer. I was… delayed."

Dean made a disbelieving noise. "That's convenient."

Cass looked at Castiel, taking in the disheveled angle of his trench coat and the bags beneath his eyes. She recalled that Uriel had said that Castiel was busy, and though she couldn't see any blood on him, she was quite certain when she said softly, "They hurt you."

Castiel hesitated, then nodded. "Yes. I regret to say that I may not have escaped if they had not let me go, to serve as messenger."

Cass reeled for a moment, trying to absorb the fact that her meddling with the timeline really had nearly gotten Castiel killed. She felt nauseous at the very thought. She'd already gotten Anna killed, and now Sam, too. Who would be next?

"Alright," Dean said, his tone business-like. "Let's go."

Castiel furrowed his brow at him. "Go?"

"To get my brother back," Dean said impatiently. "Let's go."

"I can't let you do that." Castiel looked genuinely confused by Dean's demand. "Have you forgotten that breaking the first seal is the first step to unleashing the Apocalypse?"

"Does it look like I care?" Cass could confirm that it did not. He looked ready to march down to Hell himself, whether Castiel was with him or not. "I'll deal with the Apocalypse. Hell, I'll deal with Lucifer himself if I have to. But I'm not gonna let my brother rot in Hell, not 'cause of me."

"There may be another way," said Castiel slowly, carefully. "To retrieve Sam, without breaking the seal."

Dean waited a beat. When Castiel did not immediately continue, he said, "Well? Spit it out."

Castiel's brow furrowed in confusion again. Cass would have found that funny if she didn't feel so hollow inside. In a ragged voice, she told the angel, "He means 'explain.'"

Castiel blinked, then nodded and obeyed. To Dean, he said, "The rebel angels and the legions of Hell will not make the same mistake they made with you. Anna had the element of surprise, but this time they will be ready. Your brother will be heavily guarded." He turned to direct his next words to Cass. "There is no way to succeed through stealth. And the few angels I've found who are truly loyal to humanity are not enough to wage a successful assault."

"I'm not hearing a solution, here," said Dean impatiently.

"My solution is to send someone no angel or demon would dare to touch." He was still looking at Cass, and she had an awful feeling she knew exactly why.

"Me," she breathed. "You want me to go."

"Angels are not permitted to bring you harm," Castiel reasoned, speaking quickly. "And should a demon try to do so, an Archangel's wrath would fall upon them. Their defenses could not harm you."

"That didn't stop Uriel from knocking her out," Dean said gruffly. "How do we know they won't just put her to sleep again?"

"Or lock her up in a nice, safe dungeon?" Bobby added. Cass wrapped her arms tighter around herself, trying not to betray just how deeply that thought terrified her. Castiel was undeterred.

"They would have to catch her, first."

"Catch me?" Cass repeated, confused. Castiel looked back at her with his very blue eyes, not blinking. Cass stiffened. "You're talking about possessing me. Aren't you?"

Castiel inclined his head. "I cannot lay siege to Hell on my own. You may be invulnerable to harm, but you are still human. You are not fast enough or strong enough to resist capture. Together, and only together, we might free Sam without breaking the first seal."

"You wanna possess somebody? Possess me," Dean said firmly, stepping forward. "They're not supposed to hurt me, either, right? I thought I'm supposed to be a vessel."

"There is nothing stopping them from killing you now and resurrecting you when it is convenient," said Castiel bluntly. "More importantly, I would not risk your presence in Hell. Even if I were to possess you, your hands shedding blood may still be enough to break the first seal."

"The first seal breaks when a righteous man sheds blood in Hell," Cass recited, then sighed shakily. "No matter how loosely you interpret it, there's no way I could be mistaken for a righteous man."

Castiel nodded. "If you truly wish to save Sam, and prevent the first seal from breaking, this is the only way."

She didn't want to go to Hell. She didn't want to let Castiel possess her, either, not when she remembered how Jimmy Novak had described the experience: like being chained to a comet. She didn't know if she had the mental fortitude to put up with an experience like that, and now Castiel was asking to take control of her body so he could lay siege to Hell. The very idea of it terrified her.

But Sam was dead. Dead when he shouldn't be. Dead because of her, and the rippling changes she'd made to the timeline. She shouldn't even be here, and Sam should be here. Sam, who'd gone on a run with her just this morning, who had taken her grocery shopping, and made her laugh, and stepped in front of Uriel to defend her without hesitation. Cass couldn't forget the unnatural stillness of his face, the blankness in his pale eyes, the feel of his rapidly cooling skin when she pressed her fingers desperately to his throat and felt nothing.

It wasn't right.

"Okay," she croaked, looking into Castiel's too-blue eyes and nodding. "I'll do it."

Author's Note: Before anyone complains about cliffhangers, just know that I was initially going to put the first half of this chapter at the end of the previous chapter and just leave Cass knocked out in a parking lot for a week before updating again ;) Thanks for all your reviews, everyone! Next time we see… Cass squared? Cas2? Cass-tiel? Casss?