au inside an au?

Part two:wrong turn

Sam and Dean pulled up to the crime scene a few short hours later. Dean swings into a parking spot crookedly. Sam fishes around in the glove box for their badges. He hands Dean his and slides his own into the inside pocket of his suit. They get out and approach the sheriff.
"Special agent Carson,and this is my partner agent Stevens." Dean says motioning to Sam. They flip their badges down momentarily then flip them back up, not allowing further examination by the sheriff.
"Uh, yes" he says. "Maggie Roberts" he says waving a hand at the body. "She was a good kid. Good grades. Lots of friends. Listened to her mama." He took his hat off and held it to his chest, looking down. Sam looked down as well, no doubt feeling sorry for the girl. Dean felt bad, sure it was a horrible thing, but it happened, it's over, they can't fix it so why dwell on it?
"De- um, Agent?" A familiar voice comes from behind them. Dean turns with his eyebrows raised and resists the urge to hug Cas for just getting there. He pushes his happiness down.

"Agent." He says nodding to Cas. Sam nods as well.  "Sheriff" Dean says turning back. "This is special agent.." he looks at Cas. Cas wedges  between Sam and Dean and takes the sheriff's hand. "Gavin." He says.
    "Well I don't mean no offense Agents, but ain't two FBI enough?"
They look at each other.
"Actually, agent Gavin is trailing us." Dean tells him. At the sheriff's confused look he adds "You know, watching the case, training, stuff like that."
"Stuff like that."Cas echoes and Sam nods.
The sheriff finally left after briefing the boys on the case. Not much clues. Sam was talking to a shy, hunched over woman. The witness Dean guessed. He and Cas just started to walk over when she screamed and pointed at an uglier hunched over woman "THATS HER!!" She screeched ducking down and covering her face. Sam reached for his gun but the witch had already stolen a car and drove away. "I'm on it." Dean said running to the car.
He sped away after the witch. Since when do witches steal a fricken car?
Cas appears next to Dean in the car. "I can stop her." He tells Dean. He knew Dean wouldn't want him in the line of fire, but also knew Dean wasn't gonna catch that witch in a car.

The witch suddenly stops and the impala swings around following suit. Both cars were enveloped in a cloud of tan smoke. The witch steps out of the car and prowls toward them slowly and gracefully, without a care in the world. Yeah? Well think again you son of a bitch I've got witch killing bullets Dean thinks.  "Dean." Cas says with a warning in his voice. Cas puts his hand on Dean's shoulder just as the witch holds out her hands and shoots something that looks like green lighting at the impala. Dean looks over at Cas with tears in his eyes.
"I love you" he says it but Cas can barely hear him.
"I love you too Dean" Cas says, still holding on to Dean's shoulder.
They don't look away from each other's eyes.

The light strikes the car resulting in deadly looking green and white flames. The car explodes with a massive roar that sounds like nails in a bucket being shaken by your year right by a passing train. Dean has tunnel vision. Everything is rainbow as he looks over at Cas. His hand had come off Dean's shoulder and was now suspended in the air by their heads. Cas was bleeding and Dean knew it was because of him. Because he brought Cas here. Cas's eyes are closed but he doesn't look peaceful. He looks dead. But no that can't be right. He's breathing.
Panic swells inside of Dean's chest making it hard to breathe. He struggles to get out of his seatbelt  and get to Cas. No no no he can't be dead.
Dean pulls Cas out of the car and cradles his head in his lap.
"Cas." He says putting his hands on Cas's face. "Cas, baby come back to me,please come back." Dean begs. He didn't want to admit that Cas wasn't coming back. "CAS!" Dean yells his name over and over and over again until he can no longer breathe. He lays next to Cas, holding his hand. He doesn't know how long it's been but everything goes dark and he can feel himself slipping away.