They thought the house was empty. After they got the family into the basement, they thought the house was empty. But as the clock struck twelve, a teenager with dark hair and sea green eyes entered the room. He was obviously as surprised as them. Then his face changed into a smile that made it seem like he didn't have a care in the world. "What are you doing here?" he asked, keeping the smile on his face.

"Kid, you need to get out of here," Dean said, urgently. "Go down to the basement."

The kid's eyes widened and then Sam noticed his them. The boy's eyes were like his own. Full of pain, suffering, and burden like this kid has seen all the world had to offer, but they also carried something that Sam's eyes had long since left behind. A spark. A spark of humor and rebellion. "What is happening?" the kid asked, pulling Sam from his examination.

Then Dean's eyes whipped towards the doorway. "Hellhound," he whispered.

"Where?" Sam asked.

Dean continued to stare at the doorway. "There."

Dean, Sam, and Ruby raced away from the door, pulling the kid along with them. It wasn't long until they barged into another room. Ruby and Sam immediately slammed the doors and threw all their weight against it to keep the hound out. Dean ran around the room, lying dust at all the entrances and the kid just stood there, the careless look replaced by one that was just dumbfounded. The hound eventually left the door, leaving the room in silence.

"And I repeat," the kid said, "what is happening?"

But everyone was too busy talking to respond to him.

"Give me the knife, Sam. I can try and fight it off."

Sam continued to shake his head, but eventually he gave in and handed the knife over to Ruby.

"Sam, that's not Ruby!" Dean suddenly yelled and she turned around and flung her arm out. Then all of them were flying towards the walls.

"Thanks Sam," Lilith said, her eyes rolling backwards to reveal her blank, white eyes.

"I'm so confused," the kid said and all eyes turned to him. Dean and Sam's eyes spoke warnings, but Lilith's eyes twinkled.

"I didn't know we would have a guest for this. Who are you?" she asked.

"Who are you?" the kid challenged. Dean and Sam both had a sinking pit in their stomachs. How stupid could you get?

Lilith shook her head and turned her attention back to Dean. "One year ago, you sold your soul to bring your brother back to life. The time's come for you to pay up."

She opened up the door with a smile. "Sic 'em, boy." And Dean could only hear the growling as the hellhound barreled through the door, headed straight for him.

"Mrs. O'Leary?" the kid's voice broke through the tense silence. And apparently Lilith's concentration too because the boy dropped to the ground. The hellhound paused in its mission and instead bounded off towards the kid.

"No!" Dean shouted. Then he turned to Lilith. "The kid has nothing to do with this. Let him live!" But it was too late. The hellhound had already reached the boy. The kid's arms shot out and wrapped around the hound. Then he fell backwards as the hound began to lick his face.

"I know, I know," he said, laughing, "I missed you too. I thought you were still in New Rome with Tyson. What happened?" The kid continued his one sided conversation as the three surrounding them looked at the two in shock.

"What the hell is happening?" Lilith asked, angrily. "Who the hell are you, kid?"

"Percy Jackson. Who are you?"

"The Percy Jackson?" Lilith asked, ignoring his question.

"The one and only," the kid said with a smirk settling onto his face. "Now, who are you?" The smirk was still there, but his eyes were cool and his voice was deadly serious.

Who is this kid? Sam wondered as he watched Lilith become more and more unsettled. She didn't answer Percy and eventually Dean took the liberty of answering for her.

"This is Lilith. She's a demon who was supposed to kill me and take my soul."

Percy moved his eyes from Dean back to Lilith. "And you were going to use Mrs. O'Leary to do so?"

Lilith sputtered as she tried to defend herself. "I- uh- I- he- she-she's a hellhound. She's supposed to help us demons."

"Why have I never heard of demons before?" Percy asked. "I've been to the Underworld plenty of times. Do you work for Hades?"

Lilith stuttered. How dare he mention that name? "Not technically…"

"But yes," Percy said, finishing her sentence. She glared at him. "Now I need to make a call."

He pulled his arm off Mrs. O'Leary to pull out his cell phone. Get him, boy. Lilith thought, desperate to be rid of this "hero". But the hound just stared at her, drool dripping off its face then it turned to Percy and have him another lick. Percy smiled and ruffled her fur.

"I'm trying to call Nico, O'Leary."

"The devil's boy?" Lilith asked, unable to hide her surprise.

"The "devil"? Is that what you call him?"

"You know the power a god's name can wield."

Percy shot her an odd look. "Okay, well, whatever floats your boat."

"God?" Sam asked. "Who's dealing with God."

"Little g god," Percy replied. Then whoever he was calling finally picked up. "Hey Nico, can I ask you a question?...I know that was a question…Fine, can I ask you another question?...Are there demons in the Underworld?...Why haven't you ever told me?...No I don't tell you everything about the sea…I see your point. Goodbye. Wait, is Will with you?...Are you sure he doesn't want to talk to me?...Fine. I didn't want to talk to him either. I'll see ya." The call finally ended and Percy turned back to the three adults. "Nico backs up your story."

"Who fucking are you?" Dean finally snapped and asked.

"Percy Jackson, Son of Poseidon and Sally Jackson. And this is Mrs. O'Leary," he said, pointing at the hellhound.

Poseidon? Sam mouthed to Dean.

"Well, I'll leave you all to it. Have a nice day." The kid sauntered out of the room with the gigantic hellhound trotting next to him.

Lilith continued to watch them, shocked and, honestly, a bit scared, and Dean wrenched the knife from her grip. "Oh you are so dead," he said as he stabbed the knife into her chest.

The brothers sat back-to-back, celebrating Dean's extended life. "I think the world just got a whole lot bigger. Did you hear what that boy was talking about? He's Poseidon's son and demons apparently work for Hades," Sam said.

"He said his name was Percy Jackson, right?" Dean asked. "Didn't a Percy Jackson go missing like last year or so? And who makes friends with a hellhound? Goddamn, our lives are way too complicated."