I was looking for Cain to try to find a way to get the Mark of Cain off of Dean, torturing every Demon I could find that could lead me to Cain.

Now, in an abandoned warehouse, I had a Demon in a Devil's Trap.

My phone was ringing on the table.

"Gonna answer that?" the Demon asked.

"Not at this moment," I answered.

"You're wasting your time," the Demon told me. "I told you, I don't know where he is. Me and Cain ain't friends. He kills Demons. Low-level guys like me keep our distance."

I looked at him in feigned intrigue. "You sure about that?" 

I slit my Angel Sword across his arm and bare chest, making him flash with bright light and scream in pain.

 "All right!" the Demon told me. "All right." I stood in front of him. "He's been seen, past few months, making passes through Bogg's marsh, one county over. No one knows why, what for. Like I said, we keep our distance."

I pointed the tip of my Angel Sword directly in front of the Demon's eye. "And that's all you know?"

"Yes," the Demon answered. "Yes, I swear."

I lowered the sword to my side.

The Demon sighed, hanging his head in relief.

"Okay," I told him.

I stabbed him in the stomach, killing him, making him flash with bright light.

*     *

I found Cain's burial site, filled with dozens of bodies, looking around. I called Sam.

"Hey, where you at?"

"Illinois."

"Hey, Ava, we got a lead. Cain abducted a Texas death row inmate named Tommy Tolliver."

I found a man's dead body wearing a white sneaker with the letters 'TDJC' on the bottom. "He's dead."

"How do you know?"

"Call it an educated guess. Cain has been very busy."

I stood, looking around the burial site.

"Okay, where are you? We'll come to you."

I knew someone was watching me. "I'll call you back."

I hung up, turning around.

Cain was standing there. "Hello, Octavia."

*     *

I looked at Cain in incredulous contempt. "What have you done?"

"These bodies?" Cain asked. "Just cleaning up a mess I made a long time ago."

"Cain, I know what you were," I told him. "But you'd resisted for so long."

"What can I say?" Cain asked. "I got the taste back." He stepped closer. "With Abaddon's army gunning for me, I had to take up arms again, and I liked how it felt."

"Those were Demons," I told him. "These..."

Cain knelt down to pick up a muddy stuffed teddy bear. "Humans. Eh, the Mark thirsts for all kinds."

"This is a massacre," I told him.

Cain stood. "Yes. And soon it'll be genocide." He dropped the bear. "My children, my whole poisoned issue. A lot of them out there right now... killers, fighters, thieves, some more peaceful than others. But they still carry it... the disease. If the Mark wants blood, I'll give it mine."

"You'll kill them all?" I asked. "You are Adam and Eve's firstborn. Your descendants are Legion."

"At most, I'm culling... one in ten," Cain told me.

"Of everyone," I told him.

"I've got time," Cain told me. "How's Dean, by the way? I hear he did good. Took Abaddon down. He's not well."

"Even with the First Blade hidden, Dean is losing his fight against the Mark," I told him. "If we don't find a cure..."

"There is no cure," Cain told me. "I'm living proof of that. But don't worry about Dean. I'll get to him, in due time." I slid out my Angel Sword from my jacket sleeve into my hand. "Sorry, Octavia. You're not on my list."

Cain disappeared, leaving.

*     *

I went to the Bunker to tell Sam, Dean and Castiel.

Dean was looking at files.

Sam was sitting at the laptop.

"I'm sorry I couldn't bring better news, Dean," I told him.

"It's not your fault, Ava," Dean told me. "Thank you."

"All right, the sheriff gave me a few more names, some preliminary IDs on the bodies," Sam told us.

"And?" Dean asked.

"And it seems to fit Ava's story," Sam answered. "I mean, there's no way to tell the relation to Cain, obviously, but he's wiping out entire families, one after another."

Dean sighed. "So who's next? Is he done with the Tolliver?"

Sam typed away on the laptop. "Uh, I think so. I mean, Leon didn't have any siblings or any other children that are on record, and Tommy was never married, so..." He sighed. "Oh, come on. Damn it."

"What?" Castiel asked.

"Tommy did have a son, estranged, who lives with his mother in Ohio," Sam answered, pulling up the birth certificate. "Austin Reynolds, 12 years old."

"Is the kid still alive?" Castiel asked.

Sam opened up a Facebook page. "As of an hour ago, yeah. He updated his status. But, I mean, come on. It's a kid. You don't really think Cain would..."

"Yes, he would," I told them.

"There were old men in those graves, women," Castiel told them. "I mean, you heard Ava. It's a fire sale. Everyone must go."

Dean turned to leave.

"Where you going?" Sam asked.

Dean turned to face us. "We know where Cain's gonna be. The kid's in danger."

"Okay, so what?" Sam asked. "We track him down to Ohio, and then what?"

"Then I'll do what I have to do," Dean answered. "I'll kill Cain."

*     *

Dean was in his room, taking a shotgun off the wall, putting it into a bag I was packing on the bed.

Sam was standing nearby.

Castiel and I were standing in the doorway.

"When he gave me the Mark, Cain said that this day would come," Dean told us. "That after I killed Abaddon, I would have to come and put him down."

"Great," Sam told him sarcastically. "So you're taking orders from a madman."

"No, he wasn't mad them," Dean told us. "Cain resisted the mark for a long time, then I came, kicking up trouble about the Blade. I sent him down this path. This is on me."

"It doesn't mean you have to be the one to go after him," Sam told him.

"Yes, it does," Dean told us. "And there's only one thing that can kill him."

"The Blade," I finished.

"Dean's right," Castiel told us.

"Dean, wielding the blade against Cain himself..." Sam trailed off worriedly. Dean held a hand over the Mark. "Win or lose, you may never come back from that fight."

Dean nodded barely. "I know."

*     *

Dean called Crowley.

"Well, well, well, if it isn't--"

"Cain's back. He's gone dark, and I need the Blade."

"Why would I do that for you?"

"Because you have as much reason to want Cain off the board as anyone. Cain has a kill list, and you're on it." I raised my eyebrows. "What do you say, Crowley? You in?"

"Yes."

"Good. I'll text you the location."

Dean hung up, looking at us.

*     *

We were outside Austin's house, outside a barn.

Sam, Dean and I were standing nearby the barn.

Castiel walked toward us.

"Kid here?" Dean asked.

"He's nearby," Castiel answered. "Upstairs in the barn. He's playing with a basketball."

"Cain will strike soon," Dean told us. "Maybe tonight, maybe tomorrow, but soon." He looked at Sam. "And when he does..."

"Yeah, I got it," Sam told him. "You charge in with the blade solo. And the kid? What, we just watch and wait until Cain attacks? I thought this was a rescue mission."

"We save the kid after Cain shows," Dean told us.

"We know what Cain's after," Castiel told us. "That's our only advantage. We want to trap Cain, we use it."

I scoffed, shaking my head. "A 12 year old as bait. I can't believe what I'm hearing."

We heard Crowley behind us. "Neither can I."

We turned to face Crowley.

Crowley walked closer.

"What's the matter, Crowley?" I asked. "You suddenly grow a conscience? Too good to put a minor in danger?"

"Don't give a damn about the kid," Crowley told us. "I'm talking about the risk to us."

"There is no us," Dean told him. "You're here for one reason. That's to hand me the Blade."

"Yeah, about that," Crowley told him. "Seeing as this is shaping up to be one of those, uh, two-step capture, then kill kind of deals, I think your buddies would agree it's better to keep the Blade out of your hands until we've got Cain sewn up, just to be safe." Dean looked at Sam. Sam shrugged in agreement. "Now, back to this plan of yours..."

*     *

Austin was playing basketball inside the barn.

Castiel was watching from outside the window, turning away toward Dean.

Dean walked closer. 

"So... if this works and we capture Cain, then what?" Castiel asked.

"We'll cross the bridge when we c..." Dean trailed off, correcting himself. "If we come to it. You know, last week, when I said that I would go down swinging when the time came? I meant that I was at peace with that. I didn't realize the time would come so soon. You know, like right now. I'm scared, Cas."

*    *

Austin walked out of the bar, carrying the basketball. He had earbuds in his ears, listening to music. He heard something, turning around. "Someone there?"

Austin turned back around.

Cain was standing there. "Hello, Austin."

"What are you doing here?" Austin asked.

"I'm here to kill you," Cain answered, pulling a knife from his jacket.

"No, you won't," I told him. He looked at Austin. "Run!"

Austin ran toward the barn.

Sam led Austin inside.

Cain looked at me. "You can't stop me."

I raised a hand toward Cain, my eyes glowing bluish-white from within, light emanating from my hand.

Cain's hair blew back a little, as if a breeze went by.

I returned to normal, puzzled.

Cain pointed his knife at me, flicking it to the right.

My Angel Sword flew out of his hand.

Cain flicked his knife to the left.

I was thrown through the air, crashing into the side of the truck, landing in the truck bed.

Cain walked toward the barn.

Sam turned toward Austin.

Cain appeared behind him.

Austin turned to face Cain. "Don't. Please don't."

Cain looked at Sam, stabbing Austin in the stomach.

Austin disappeared in a cloud of purple smoke.

Cain looked at Sam. "Illusion spell."

"Oh, yeah," Sam answered. "The real Austin in long gone."

"18th-century magic," Cain told him. Crowley walked into view. "If I had to hazard a guess, rune of Amaranth."

"Good eye," Crowley told him. "Something I picked up from my mother."

"Well, I know you fear me," Cain told him. "I can only assume." He used his foot to clear away some of the hay from the floor to uncover a Devil's Trap. "Oh. Clever. Won't hold me for long, you know."

"It won't need to," Sam told him. Sam and Crowley walked outside. Cain saw Dean outside. Sam closed the doors. I walked toward them, holding my head. "Ava, hey, you okay?"

"I'm fine," I answered. "It worked."

"Yeah," Sam agreed.

"My turn," Dean told us.

"Dean, look," Castiel told him. "We want to help."

"No," Dean told us. "No, with you in the ring, it'd just be a liability."

"Dean?" I asked.

"I'd be too worried about what he could do to you," Dean told us. "Or what I could. Plus, I need you guys out here to take out whatever comes out of there. And I'm serious. I mean, whatever comes out."

Sam, Castiel and I didn't answer, not happy about it.

"Happily," Crowley told him. Dean held his hand toward Crowley. Crowley held up the First Blade. "What guarantee do I have that you'll give it back when you're done?"

"If I survive and I come out of there and I don't give it back, you'll all have a much bigger problem on your hands," Dean told us.

Crowley knew he was right, handing Dean the First Blade.

Dean felt the power, the focus, the darkness, instantly, taking a breath, resisting the feeling.

"Dean?" Sam asked worriedly.

"I'm good," Den told us, walking up the flight of stairs, looking over toward us.

Dean took a deep breath, sliding open the barn doors, walking inside, closing the doors behind him.

*     *

I could hear what was going on.

"Hello, Dean," Cain told him. "At a loss for words, my son? Allow me. This is the part where you tell me it's not too late, and I can lay down arms, abandon my mission. 'We don't have to fight'."

"I'll spare us the formalities," Dean told him. "You're past talking down. Cain, you're fully mental."

"Oh, I prefer to think I've finally gotten clear," Cain told him. "When I made my bargain with Lucifer, killed Abel, I released a stain upon the Earth, a stain deeper and far more lasting than mere precedence."

"Your bloodline's tainted, so you say," Dean told him.

"So I know," Cain told him. "Not all killers are my descendant, and not all my descendants are killers, but enough are. Enough for me to know that extinguishing them is the least I owe this world. Can you honestly tell me that Humanity's not better off with few Tommy's, and fewer Leon's... Fewer you's?"

"And what about the kid?" Dean asked.

"He could go either way," Cain answered. "I prefer to be thorough. How's it feel, Dean, to be holding the Blade again?"

"It feels like a means to an end," Dean answered.

"Then do it," Cain told him. There was fighting. "That seems a bit weaker than I would expect from you with the Blade. I think you can do better. Unless... You're holding back. What is it, Dean? Do you think if you hold back just enough, you won't succumb, that you'll leave this fight the same as you entered?! Look to my example, boy! There is no resisting the Mark or the Blade. There is only remission and relapse!"

"You told me that this day would come," Dean told him. "You told me that I would have to kill you."

"Is that so?" Cain asked. Glass shattered. "I'm afraid you've misunderstood my intentions here, Dean. When your pet Angel found my burial site, I thought about ending her, and swatting her like a fly. But then I thought about you. Your biggest weakness, the thing I noticed the moment I met you, your courage, your reckless bravado. I let her go, knowing that she would report back to you, knowing you would bring into battle the one thing that can kill me. The one thing I truly want. Oh, it's been too long. That old feeling makes me wonder how I ever had the strength to resist. This may be hard to believe, in light of what I'm about to do to you, but I care about you, Dean. I truly do. But I know I'm doing you a favor. I'm saving you."

"Saving me from what?" Dean asked.

"From your fate," Cain answered. "Has it never occurred to you? Have you never mused upon the fact that you're living my life in reverse? My story began when I killed my brother, and that's where your story inevitably will end."

"No," Dean told him. "Never."

"It's called the Mark of Cain for a reason!" Cain told him. "First... first, you'd kill Crowley. There'd be some strange, mixed feelings on that one, but you'd have your reason. You'd get it done, no remorse. And then you'd kill the Angel, Octavia. Now, that one... that I suspect would hurt something awful. And then the Angel that lost his Grace, Castiel. You would barely have the strength to move on. And then! Then would come the murder you'd never survive. The one that would finally turn you into as much of a savage as it did me."

"No," Dean told him.

"Your brother, Sam," Cain told him. "The only thing standing between you and that destiny is this Blade. You're welcome, my son." I heard him scream. "What's the matter?"

"Tell me I don't have to do this," Dean told him. "Tell me that you'll stop. Tell me that you can stop!"

"I will never stop," Cain told him.

I heard the Blade plunging into skin, flesh, blood and bone.

*     *

Dean walked down the stairs toward us, beaten and slightly bloody.

"Dean?" I asked.

"Dean, the Blade," Crowley told him. Dean looked at the Blade in his hand, walking closer, handing it to Castiel. "You lied to me."

"It's not the first time today," Dean told him. "Cain's list? You weren't on it."

Crowley seemed hurt, disappeared, leaving.

Dean was in shock, nearly collapsing.

Sam caught him. "Hey, hey, hey. You did. Dean, you did it."

*    *

Sam, Dean and I were in the bunker.

Dean was sitting at the table, drinking coffee.

Sam and I stood nearby.

Sam was making coffee. "Dean, um, you know, what you did back there? It was incredible. You know, if you can do that without losing yourself..." He looked at Dean. "That's cause for hope, even without a cure."

Dean nodded. "Yeah. Maybe."

Castiel walked in.

"So, where's the Blade?" I asked.

"Somewhere safe," Castiel answered.

"Good," Dean told us. "Well, if you guys will excuse me, I think I am gonna go sleep for about four days." 

Dean stood, walking toward the door, pausing to pat Castiel and me on the shoulders.

"Of course," Sam told him.

Castiel looked between us, following Dean out of the room to talk to him alone, leaving.

Sam sat at the table.

I sat next to him, putting a hand on his arm. "This is a good thing." Sam didn't answer. "Sam?" 

Sam had tears in his eyes, sighing. "Ava... Dean's in trouble."