Sam and Dean stopped, hearing the familiar rustle of wings behind them. They turned around.
Castiel stood still as he always did. His eyes searched the brothers with soulful purpose, expression blank.
"Hello, Dean, Sam," Castiel said, a nod of his head at each brother. He took a step forward. "I've come to warn you."
Dean narrowed his eyes. "What? Warn us of what?" He approached Castiel, reaching out to him. "Cas, what's wrong?"
Castiel blinked. "I don't know."
"You don't know? What do you mean, 'you don't know?'" Dean grabbed Castiel's arm tightly, causing the angel to look down at the grip on him. He just stared at it.
"Cas? What's going on?" Sam asked. He walked up and stood next to Dean.
"I don't know. There's something coming. Something dangerous. I can't tell what it is, but it's huge. You need to be prepared," Castiel murmured. He looked up and into Dean's eyes. "It's angry. And it knows. But what it knows, I'm not sure. I can sense it." Suddenly, the angel grimaced, legs failing him as he fell to the floor in a daze. His eyes squeezed shut, nose wrinkled as Dean caught him halfway through his fall. Castiel gasped, eyes flying wide open. He grasped Dean's arms, trying to stand up but failing.
"Cas! Cas! Can you hear me?" Dean yelled, shaking the angel.
"D-Dean, you have to get out of here. Leave. Just leave. I don't want you to get hurt." Castiel felt his legs give out completely. He fell to the ground, Dean so unprepared for the sudden weight that he nearly fell over as well. The angel lay unmoving in the dirt. Dean got onto his knees and shook him violently, gripping the lapels on his coat.
"Sam, don't just stand there! Help me!" Dean snapped as he tried to pull Castiel up. Sam jerked into action and went around to Castiel's head, taking him under the arms while Dean grabbed his legs. Together, they moved the angel to the Impala that sat about twenty yards away. Dean opened the back door and they maneuvered Castiel so he was laying on the seats.
"What. . what just happened?" Sam asked, staring at the angel laying limply in the back of their car.
"I don't even know," Dean muttered. He crossed his arms and leaned on the Impala. "And apparently, neither did Cas!"
"Whatever's coming is big news. We need to find out."
"From who? If Cas didn't even know, then who would?"
Sam gazed at his brother. "Then what do we do?"
"We'll have to wait until Cas is better." Dean glanced down at the unconscious angel. He bent down and gave Castiel's foot a quick shake. With a gasp, Castiel shot up, shocking both brothers nearly out of their skin.
"I have to- I have to go!" Castiel shouted. Before any of them could say otherwise, the angel vanished on the spot. He left only a deep red stain covering the place where he laid.
The agents on the helicarrier were working steadily. Clicking of computer keys and shoes walking across the polished floor of the ship were accompanied by voices talking and yelling. The roar of the engines buzzed dully in the background. It was only when a bloody man appeared right in the middle of the room and fell unconscious that the yelling increased. Workers stopped what they were doing and rushed forward. The voices were fading together in a blur, yells increasing in volume echoing throughout the room.
A man walked in, one eye covered by an eye patch. He was accompanied by a woman with brown hair. "What's going on?" Fury demanded, stomping down the stairs towards the crowd of people.
"He just appeared, sir, then fell unconscious," a man replied. Fury narrowed his eye and pushed his way through the people, who quickly stepped off.
Dropping down to one knee, Fury checked the man for a pulse. "He's alive. Get him to the infirmary!" At once, agents came through with a stretcher and transferred him to it, then rushed off.
"He just appeared? That's what his story is?" Agent Romanoff asked as the trio walked down the hall.
"Yeah, I guess. Wherever this guy came from, I don't trust him. Might be working for Loki," Fury said.
"Is he awake yet?"
"No. And the reason I brought you to see him is that his blood was tested and the information came back as 'undefinable.'"
"Alien?"
"Most likely," Agent Hill added in from the opposite side of Fury.
"Interesting. Should I tell the others, or. .?"
"Don't. Not until we find out what this guy is," Fury said. As he finished his sentence, he pushed open the doors to the hospital area of the helicarrier. The trio walked down the hall, passing a few doctors and nurses along the way. At the end of the hall was a door, which was currently housing the interesting man.
"Hello, Director Fury. Here to see the patient?" a woman asked.
"Yes, we are," Fury replied.
"Well, good, because he just woke up."
Hiyah people! Yes, this is another Avengers crossover fanfic. For those of you waiting for Blue skies and Blue Boxes, don't fret. The updates on this story probably won't consume all my time and effort. I'm working. While I'm watching Supernatural. So. . . yeah. Great show. I love Castiel. Btw, this is set somewhere in season 5? Before he became God, anyways.