It was complicated to describe, the feeling of something else taking over you. But it wasn't just controlling his body and his mind, it was destroying them. It was eating away at his instincts, pulling apart his power with an almost gleeful force. It was as though it had been expecting a biscuit but given a three course meal; it had been expecting a human, but given a Grimm. Because to demons, a human and a Grimm look identical. Most demons believe that Grimms aren't even real. But now this demon had discovered the truth. However, what this small demon did not realise was the power of a Grimm. But that was all about to change.

After much talking and no small amount of bribing the guards, Dean was finally allowed back into the same cell as his brother. They hadn't spoken in a while, simply sitting there in silence. Both of them had quickly realised that there was no way they could break out of here. Even if they could, there was still the problem of the detective who knew far too much about them. Who was he? How did he know so much about them? Was he even human? So, they were forced to sit and wait until Cas turned up, and in the meantime they needed to find out more about this detective. As if Fate herself was there in the room, that very detective opened the door and walked in. Instantly, Dean flicked his eyes over to Sam; something about him was different from last time.

"Sam, Dean, how nice to see you again" the detective offered a forced smile which neither of the brothers returned. Slowly, he walked over to them until he was leaning against the bars of the cell, staring in at them. It was then that Sam noticed the line of sweat trickling down the man's face and now he knew something was definitely wrong. His breath seemed to be coming out in small, sharp bursts and his hands gripped at the metal bars of the cell until his knuckles were white. But his face still held a smug half-smile.

"What do you want?" Dean asked warily; he wasn't sure what it was but something was definitely off about this guy.

"Oh, I've just come to see you. I've got you right where I want you; nicely packaged in a cell, no escape. Perfect!" the detective smirked and his eyes flickered until they were completely black. Both Sam and Dean instantly stood up. But then something happened that no one had been expecting. The detective fell forward and gasped desperately for breath for a few moments. And when he looked up, his eyes were no longer black.

"W-What's happening?" the detective's voice was panicked. But neither of the Winchester brothers had ever seen anything like this before. Had this guy just internally fought off a demon?

"What the hell" Dean muttered, staring at the detective like he was a cross between a bomb and a piece of artwork.

"It's controlling me. I don't- what's happening?"

"Calm down" Sam started to speak but his words trailed off when he realised he had no idea what to say.

"Exorcizamus te, omnis immundus spiritus, omnis satanica potestas, omnis incursio-" Dean started to say, his eyes fixed on the detective.

"Dude, what are you doing?" Sam cut him off as the detective fell to his knees in both confusion and pain.

"What does it look like I'm doing, Sam?"

"You can't, we don't know what's happening inside this guy. Exorcising the demon could kill him"

"And not exorcising it could get us all killed!"

They stared at each other for a moment until Sam gave in and looked away. Dean took a step forward and focused his eyes on the detective who was now on his knees on the floor.

"You still there, buddy?" Dean called out, hoping the guy still had control over the demon. He looked up to see scared eyes looking back at him. Scared, confused, pained, but definitely human. With that knowledge, Dean continued the exorcism. Almost instantly the detective lost control and the demon took over his body once more. But for some reason, it didn't leave. Instead, it stood as though trapped in place and screamed and begged for Dean to stop. Dean completely ignored the creature. But as Sam stood and watched, he noticed that this demon was not like the others. It seemed almost sad. Most of what it was saying Sam could not really hear but just as it was expelled from the body it screamed something that even Dean heard.

"He's a Grimm!"

It felt as though someone had reached inside him and pulled as hard as they could on his lungs. He could hardly breathe, his head was pounding and his entire body was sweating. He found himself on all fours on the floor, panting and shaking. Everything was silent apart from his own breathing. But that silence did not last long.

"Are you okay?"

Nick's head snapped up to be met with Sam and Dean Winchester staring at him from the other side of the cell bars. Sam looked partly scared, partly worried and Dean was just looking at him like he was The Mona Lisa. He wasn't sure which one made him more uncomfortable. Nick tried to ask what the hell had just happened but all that came out his mouth was a strained croak. He tried to stand but fell back down almost instantly.

"Hey, take it easy" Sam reached out slightly, concern obvious in his voice.

"We just saved your life, so would you mind getting us out of here?" Dean scowled, which earned him a disapproving look from Sam that he completely ignored. Nick's muscles began returning to normal and slowly he pulled himself up off the floor and leant against the cell bars for a few moments before reaching into his pocket, pulling out the keys, and unlocking Sam and Dean's cell.

"What just-" Nick started to ask once they were out of the cell but was stopped short as a blinding light suddenly appeared between them. Nick flinched and covered his eyes for a moment before looking up to see a man had suddenly appeared next to Dean. A man in a trenchcoat, who's skin moved and glowed. It was the same man he saw on the night of Sophia's death.

"Cas" Dean smiled at the man.

"Step away from him" Nick said shortly, his eyes fixated on the mysterious man whose name appeared to be Cas. The man stared at him for a moment before taking a step back.

"It's him"

"What do you mean 'it's him'?" Sam asked, his eyebrows raised. Silence fell over the four of them as Nick and Cas stared at each other, both confused and pretty scared.

"Okay, what the hell is going on here? Why are you two staring at each other like you just fell in love in a 90's rom-com?" Dean growled, his eyes flicking between the two men.

"This is the man I was talking to you about" Cas stated, not taking his eyes off Nick.

"Okay, so first you fight off a demon and now you can see angels. What the hell are you?" Dean kept his eyes on Nick, who sighed. He knew that they all seemed to be as confused as each other, so the only thing Nick could think of doing was telling them the truth. The whole truth.

"My name is Nick Burkhardt and I am one of the last Grimms"

"A Grimm? But you're not meant to exist. You're simply a myth of something my Father failed to create" Cas took a step towards him and it took all of Nick's willpower to not step back.

"Woah okay, what the hell is a Grimm?"

"Dean, seriously? The two Grimm brothers, who wrote the Grimm tales. You can't have not heard about that before" Sam turned to his brother.

"So now I've answered your question, you can answer mine. What type of Wesen are you?" Nick narrowed his eyes at Cas.

"I am no Wesen. My name is Castiel and I am an angel of the lord"

Nick wanted to retaliate with something but his words died on his lips. The way the three of them were looking at him made Nick want to shiver. He had no idea what they were, but they seemed to have little idea of what he was either.

"We need to get out of here" Nick knew that he had just broken out two of the most wanted criminals of the past ten years, but he also knew that there was more to this than it first seemed.

"How do we know if we can trust you?"

"You don't. And I don't know if I can trust you. But I know you're not cold hearted killers. You might even be what some people class as the 'good guys'. So for now, we need to go someplace safe where we can talk about what the hell just happened"

Dean looked like he was about to say something, but his brother cut him off.

"Where do you have in mind?"

"My house. I have a surprisingly big network of people who are used to this kind of crazy. And I'm a detective, so no one will suspect anything"

No words were spoken but a silent agreement seemed to be made between the three men before Dean looked over at Nick and nodded. With that, Nick led them out to his car- careful to avoid all the CCTV cameras dotted around the precinct. Once they were loaded into the car Dean suddenly spoke.

"You don't happen to know where my car is, do you?"

"The Impala? It's round the back under lock and key, I'll be able to get it once they realised you're gone" Nick said, smirking at the concern in Dean's voice. The ride back was silent; partly awkward, partly tried. Half way there, Nick's cell rang.

"Hello?"

"Nick! Where the hell have you been?" Trubel's voiced echoed down the phone.

"Sorry, a lot of strange stuff as happened. I'm on my way back now. Just as a warning, I'm coming back with Sam and Dean Winchester"

"Woah, what?! THE Sam and Dean Winchester? The ones you just locked up for being mass murderers?"

"It's not how it seems. They're all wrapped up in this somehow. And it's my job as both a detective and a Grimm to find out what happened to Sophia"

"Okay, see you soon then" Trubel said before hanging up. They all fell back into silence until Nick pulled up outside his house and the four of them got out the car. Nick walked up to the door and stepped inside, quickly followed by the other three. Sam cast his eyes around the room, but Dean and Cas kept their eyes firmly fixed on Nick.

"Juliette? Trubel?" Nick called out, placing his keys down on the side and throwing his jacket onto the couch.

"Hey, welcome ba-" Trubel stepped out the kitchen but instantly stopped when she saw the sight in front of her. She was vaguely aware of Nick greeting her, and the two men looking over at her. But her attention was fixed on the other man. His skin held an eerie glow and it appeared to be closer to a liquid than a solid. Slowly, she reached behind herself and gripped her machete that she had left leaning against the door frame. The man's eyes soon fell on her and he tilted his head slightly. She felt his eyes looked right through her and straight into her soul. She gripped her machete harder, her eyes narrowed, and she pounced at him.