Sam sighed heavily as his brother Dean got out of the Impala to start filling up the nearly empty gas tank. The brothers had been on yet another long road trip, trying to find a way to stop the impending apocalypse. The impending apocalypse that Sam started.

Sam could hear Dean humming some kind of mullet rock tune to himself as he filled up the tank. He was trying to place the tune when he realised he wasn't alone in the car anymore.

"Hello Sam," it was Castiel, the rebel angel who was helping the brothers during these dark times.

"Hey Cas, how's it going?" Sam said wearily. Usually Sam would be happy to see Castiel sitting in the backseat of the car, but Sam was tired from the long trip and just not in the mood for making small talk with the angel.

Sam turned round in his seat to get a better look at Castiel. He was looking out of the window at the other gas station pumps with a puzzled look on his face.

"Why are you here, Cas? Did Dean call you?" Sam asked but got no reply from Castiel. He was too intrigued by the gas pumps. Sam looked out of the car window to try and see what was so fascinating to his angelic companion.

"Cas?" Sam spoke a little louder this time, trying to grab Castiel's attention away from the extremely uninteresting gas pumps. Sam was about to wave his hand in front of Castiel's face when he suddenly turned away from the window and towards Sam.

"Did you see it?" Castiel asked. Sam looked out of the window at the gas pumps again.

"See what? The gas pumps?" Sam shrugged.

"The unicorn." Castiel said matter-of-factly. Sam began to laugh out loud but stopped when he saw the serious look on Castiel's face.

"Unicorn? What? They don't exist, do they?" Sam had seen many strange things during his time as a demon hunter: shape shifters, wendigos, ghosts, werewolves, vampires, even the Devil himself. But even Sam knew that while he had seen many supposedly mythical creatures, some really were just that: mythical, made-up, non-existent.

Sam stared out of the window again, unsure of what to expect. Sam turned back to face Castiel again to say he couldn't see anything, only to find the angel had disappeared. Sam turned in his seat and crossed his arms across his chest. Seriously, unicorns?

Suddenly the driver side door opened and Dean climbed into the car, bag of peanut m&m's in one hand and a cup of coffee in the other. Without saying a word, Dean handed the provisions to his brother before putting the keys into the ignition and starting the car. Sam turned down the volume of the obnoxious mullet rock blaring out of the car's stereo, much to Dean's dismay.

"Dude, you can't turn down Metallica!" Dean reached forward to turn up the volume again but Sam grabbed his hand to stop him.

"Has Cas ever mentioned anything strange to you lately?" Sam asked, still staring at the spot Castiel had been so fixated with.

"Whaddya mean strange? Apocalypse strange?"

"Not Apocalypse strange, no." Sam looked down at his feet. Was he really going to say that word out loud? To his brother of all people?

"More like… Unicorn strange." Sam said quietly. He glanced at his brother next to him. Dean looked stunned to say the least. Sam looked away, too embarrassed to look at Dean any longer.

"Son of a…" Dean started to laugh. A lot.

"What? What's so funny Dean?" Sam felt his cheeks redden as his brother descended into near hysterical laughter.

Before Sam could display his distress at Dean's reaction, he jumped when he felt someone tap him on the shoulder.

"April Fools." Castiel said simply. Sam couldn't believe it. Dean was still laughing but was able to control himself enough to turn to Castiel in the backseat and shake his hand.

"Thanks Cas, you're the best." Dean managed to say in-between laughs. Dean faced Sam and slapped him on the shoulder.

"Come on lighten up man. Just 'cause the world is ending doesn't mean we can't have a joke."

"I still don't understand why this is so funny for you Dean? Unicorns don't exist. Sam must know that already."

"You set this up?" Sam asked Dean. Dean, still laughing could only nod in reply. Sam let himself chuckle quietly for a moment.

"Jerk." He said with a grin.

"Bitch" Dean replied.

"I still don't understand" Castiel added.