Author's Note: And here it is, the final chapter in this trilogy! I apologize for it taking a bit longer than usual, but I wanted to make sure it was perfect before I posted it :) You can interpret the last scene however you want, be it romantic or platonic. Anyway, hope you enjoy!

Disclaimer: I do not own Supernatural or anything affiliated with it.

"Castiel!"

Cas lifted his head sharply at the sound of someone saying his name. On the other side of the small glass window facing out to the backyard was Mary. Her eyes were wide with terror, staring, unblinking, at something directly above Cas' head. Huh, Cas thought numbly, reaching up with the last of his strength to place Dean on the counter and out of harm's way. I suppose the monster IS here physically after all.

Mary's face disappeared, and a second later the back door to Cas' right swung open. Mary raced inside, clutching a huge black book. There were creases running up its spine, and the front cover was a mess of cracked leather. She threw it carelessly down on the table and picked up a broom at the other end of the room before racing forward and smacking the handle against the creature's head. It turned and grabbed the broom from her, snapping it in half with its bare hand. It was larger than before, having grown from feeding off of Cas' soul. Mary bit her lip fearfully, backing up against the counter. She didn't have any weapons, not anymore. What the hell am I going to do? she wondered, her mind racing. Her eyes scanned the room wildly before landing on a rolling pin, which she snatched and hurled at the beast. The pin smashed into debris upon impact, having had apparently no effect on the thing. Mary's hand flew to her forehead, and she groaned.

Cas couldn't move. He couldn't think. It was as if he was paralyzed, caught in a spider's web with no way out. His back shook with the effort of staying upright. There was nothing he could do. He was about to die. He let his eyes fall shut and crumpled to the floor. Slowly, his mind went blank – all of his thoughts faded out, disappearing into the darkness, melding with it. He felt enveloped in a cold, unfeeling abyss. He couldn't climb out of it – it was swallowing him up. And he didn't even care.

"Cas!" Mary called urgently. The creature had her pinned against the wall, attempting to get rid of her before feasting on the last of Cas' energy. "Cas, if you can still hear me, I managed to flip through the book on my way back, and it said that the more willpower you have to fight against the monster's feeding, the weaker it'll become." She reached behind her, grabbed a knife, and stabbed it into the creature's eye. "Once it's weak enough, you can kill it with any ordinary weapon and get back to your own time," she continued. "It's a loveless being; it has no heart. That means love will weaken it the most!" The creature wrapped its claws around her throat and pitched her aside, letting her crash into the wall. She fell to the floor, unconscious.

Cas didn't move from the ground. He couldn't, really. He saw no point to it. He saw no point to anything. He was going to die, and he'd never know if the Winchesters were all right in the future. That was that. There was no way to beat this thing; why not succumb to its wishes? He had no willpower left. He had no energy left – no soul. He didn't care if he died. His mind had almost slipped away. Death was nearly upon him. All he had to do was relax, and -

Dean.

The thought was sudden. It was short. But it raced through him, firing up his nerves and shooting through his blood, making his heart pump and his lungs expand, forcing him to gulp the air down and reawaken his mind. His eyes shot open.

Dean isn't safe. Dean is exposed. Once I'm gone, the creature will go after him. Therefore, I must do everything I can to protect him.

His only focus was this order. It propelled him forward, expelling his paralysis, made him sit up and take in the scene before him. The monster had already begun moving towards the baby, but it stopped short when it sensed Cas had revived himself. Its eyes widened in shock and fear.

Cas smiled menacingly. His willpower was back – and he'd gotten it from Dean.

He slowly stood up, taking care not to over exert himself, and began taking long, leisurely strides towards the creature. It seemed to grow smaller with each step, shrinking back to its original size. Finally, Cas was only a few feet from it. They stood in a triangle, with Cas at one point, Dean at the other, and the monster in the third.

A draw. They looked at one another, daring the other to make a move first. Cas lowered his eyebrows in disgust, hatred flaring up inside of him. This beast had DARED to make a fool of him – an angel! He was revolted with himself. To think he had almost given in to death, almost let the being kill Dean – well, he would surely try to make up for it now.

Suddenly, the creature raced forward, quick as lightning, making to grab the baby. Cas started in surprise; he hadn't expected it to go after Dean again. He recovered after a moment and bolted after it, grinding his teeth. His rejuvenated energy was running out; the boost he'd received from the thought of Dean in peril wasn't enough. He slowed, exhaustion coming over him. He couldn't continue. The monster's hand was raised, ready to kill the infant.

"NO!"

Cas pushed himself forward, using the last of his energy to throw himself in front of Dean just as the beast's claw came down. Cas squeezed his eyes shut, preparing for the inevitable pain.

Nothing.

There was nothing.

Seconds passed, and then minutes, and still nothing had happened.

Cas slowly opened his eyes, blinking to adjust his pupils. As his vision cleared, he saw the creature huddled against the wall several feet away, as tiny as a child. Cas furrowed his brow in confusion. What's going on? It was just about to rip me to shreds; now it's cowering in fear. What happened?

Cas moved forward, cautiously eyeing the monster. Its breaths were shallow and staggered, and its body shuddered every few seconds. I didn't threaten it, all I did was -

Cas' eyes widened. Oh.

Love will weaken it the most.

He knelt down to the ground, feeling very tired all of a sudden. The fight had taken a lot out of him, and even though he'd recovered most of his soul now that the beast was weakened, he was incredibly weary. He was feeling generous, however, when he reached to the counter and picked up a large knife. He'd offer the creature, a quick, merciful death; he knew it was probably in excruciating pain.

He raised the knife high above him and brought it down fast upon the monster's throat, efficiently slicing its head off. Blood spurted from the wound, spilling onto the kitchen floor. Cas grimaced. He wouldn't have time to clean it, unfortunately, because a bright white light had begun emanating from his hand immediately after the blade of the knife hit the beast's neck. He would only have about two minutes before he was sent back to the future.

Cas stood up and moved over to Mary, gently shaking her arm to awaken her. She began mumbling incoherently, slowly rising to a sitting position, and rubbed her head, groaning. "What happened?" she inquired, her voice raw from screaming.

Cas held her arm and guided her to her feet. "The creature is dead, I will be departing shortly, and your son is safe." He looked down sheepishly. "Though I do apologize for the mess I've made of your kitchen."

Mary sighed, glancing at the corpse in mild annoyance. "It's okay; my husband's on a road trip with his friends for a few days, so I should have it cleaned up by then." She collapsed into one of the wooden chairs, and her gaze moved to Cas' worried face. "Could you bring me my baby?"

Cas nodded, turning around and carefully picking Dean up from his spot on the counter. He carried him over to Mary, smoothing his blanket before placing him in her arms. Mary looked at him kindly.

Cas smiled, then took a breath. "It was very nice to meet you, Mary," he said, holding out his glowing hand. "I thank you greatly for helping me, and I'm extremely sorry for all the trouble it caused."

Mary grasped his hand tightly, her face warm. "It's all right, Castiel. I have to admit, hunts are just as exciting as I remember. Really gets the adrenaline going." She huffed out a laugh, then grew somber. "But that's it. No more after this one. I have a family to care for." She released him and settled herself back in her chair. Suddenly, she lit up. "I just have one more question!" she exclaimed.

Cas' whole body was glowing now. "What is it?" he asked.

"When I was coming back, I saw you whispering something to Dean through the window. What did you tell him?"

Cas gave a small smile. "I told him that angels are watching over him."

A great burst of light showered through the room. Mary shielded her eyes, holding Dean's face against her shoulder. After a moment, the room returned to normal, and Cas was gone. Mary cradled her baby, pondering the strange man's words. Hold on a minute, she thought, sitting up straighter. Isn't that what I tell Dean every night?

A loud crack resounded through the warehouse, making Dean snap his hands over his ears. What the hell? But when he looked to see where it came from, his face lit up with joy. "CAS!" He made to run forward, but the monsters pinned him to the wall alongside his brother. He groaned in frustration. It had been going on like this for half an hour; the beasts would nearly kill him and Sam, they'd wriggle out from beneath the things' grasps, then spend the next five minutes trying distract their enemies before the cycle started over again. But this time, it seemed like there was no escape. Dean closed his eyes, his muscles tensing up – but instead of being struck dead, he heard two loud shhinks, like the sound of a sword cutting through skin, and a set of identical cries of pain. He lifted his lids to find both of the monsters sprawled on the cement floor, blood pooling around them. Cas stood behind them, holding a red kitchen knife.

"Hello, Dean," Cas said, smiling. He turned. "Sam," he greeted, bowing his head slightly.

Sam stared at him in shock. "How come you couldn't do that before?" he asked after a moment.

Cas wiped the knife on the sleeve of his coat. "Because I had a weak willpower at that time. Since then, it has strengthened considerably."

Dean blinked, then grinned. "Well, I'm just glad you're all right, man." He gently punched Cas' shoulder. "And, you know, that you got here in time to save our asses. Thanks for that."

Sam rubbed the back of his neck. "Yeah, thanks," he said. "We weren't sure how to beat those things, but it looks like you came up with something." He smiled at Cas, then pushed his hair back and out of his face. "Well, I'm gonna go get some body bags from the trunk for those guys." He nodded to the corpses on the ground, then jogged to the exit.

Dean leaned against the wall, massaging his wrist. "So, where did you end up? How'd you get back?" he asked, looking up at Cas.

Cas bit his lip and avoided Dean's gaze. "The 90s, New York City," he lied, crossing his arms behind his back. "I went into an alleyway and found a book on mythology in a dumpster-"

Dean sighed, cutting Cas off. "Dude, we both know that's not true," he said, stepping forward and grabbing Cas' shoulders. He stared him squarely in the face, forcing Cas to meet his eyes. "Now, tell me what REALLY happened."

Cas looked at him for a moment, then inhaled deeply and said, "I went to Lawrence, Kansas, when you were a baby, and I asked Mary Winchester for help researching the monster." He lifted his chin defiantly.

Dean took a sharp breath, his eyes widening in shock. He shook his head, composing himself. This wasn't anything new. Cas had done this before; HE'D done this before. "Did she?" he asked quietly.

The corners of Cas' lips quirked up. "Yes, she did."

"Was Dad there?"

"No, he was on a trip."

"Was I there?"

"I just told you, yes."

Dean rolled his eyes. "No, I mean, did I get hurt? Was I in the way of the fight?"

Cas gave a small laugh. "A bit, but don't worry, I protected you."

Dean smiled. "You did?"

Cas nodded. "That's actually what weakened the monster," he said softly. "It didn't like sacrifice."

He sacrificed himself for me? Dean thought. He felt a clench of surprise in his stomach, along with a touch of fear and displeasure. He didn't like it when people did that; he felt it should be the other way around, with him sacrificing himself for them. He shook his head. "You shouldn't have done that."

"But I did, and that's that," Cas stated firmly. He studied Dean's face. "I want you to know that you deserve it. You're worth saving, Dean."

Dean's breath caught in his throat, and his heart pounded in his chest. That's a lie. It unsettled him when Cas said things like that, because Cas knew things. He wasn't just some random person, he was an angel. An all-powerful being. And he was saying that he would die for Dean in an instant.

Dean's mind raced, trying to come up with a response. "I...That's not-"

Cas stepped forward, closing the distance between them. "Dean," he whispered. "It's okay."

Dean felt like his heart was about to burst. Was Cas telling the truth? Even after all he'd done, all the lies he'd told...Cas still thought so highly of him. Maybe...he didn't want to believe it, but he felt the idea sparking in his mind. Maybe he's right.

"Thank you." It came out all in a rush, his breath releasing as he said it, but it felt good. It felt right. Cas smiled again, and Dean felt a small flower of warmth bloom in his chest.

"You're welcome."

Author's Note: And...that's it! The end. That last scene got a bit mushy, lol, but I think it's okay. Not sure when my next story will be, but I'm back in the "writing mood", so probably soon. I hope you all liked this one!