"Press the button Cas." Dean yelled as he ran past the door. Cas looked around the room, on the console which had too many buttons for Dean to just say the button.

"Which one?" Cas replied.

"The green one!" Dean yelled back, his voice further away as the shifter chased him. Cas looked over the console and then looked again, there was no green button.

"There isn't one!" Cas yelled as Sam ducked into the room and took a look at the buttons.

"By your left hand." Sam replied before turning around and shoulder barging the shifter that had followed him. Cas looked at the button.

"But it's yellow."

"It's green, trust me." Sam yelled. Cas pushed the button and all the door closed in the old asylum. Sam let out a sigh as the shifter got caught under the door, it's body trapped and unable to move. Sam fought through the flailing limbs and pressed the blade through the shifter heart. It stopped fighting and died. Dean hit the door on the other side and Sam walked past Cas and pressed the button.

Dean stepped through and looked at the console button.

"What the hell's with this there's no green button crap. That buttons green." Dean said as he pointed at the button.

"It looks yellow." Cas replied as the brothers shared a look.

"Cas, what colour is my shirt?" Sam asked, holding his plaid shirt out so that Cas could see it.

"Grey?" Cas replied cautiously, realising that they thought something was wrong with him.

"No. It's green and red." Sam replied. Dean looked between Cas and Sam before speaking.

"Cas are you colour blind?" he asked as he furrowed his eyebrows.

"What does that mean?" Cas asked, still confused that Sam's shirt wasn't grey.

"It means you can't see certain colours. Like red and green." Dean clarified. Sam nodded along with the explanation.

"So Sam's shirt is actually red and green."

"Yeah. Didn't you know you were colour blind?"

"No. How could I have, when I was in heaven we all wore white and looked the same. I had no concept of colours, no one had taught me." Cas replied as he looked up at them both.

"What colour are my eyes Cas?" Dean asked, trying to figure out if he was green/ red colour blind.

"I know they're green, but they look yellow." Cas said simply, Dean looked confused for a moment before shrugging.

"If they look yellow to you how do you know they're green?" Sam asked.

"I know that yellow isn't a normal colour for eyes." Cas replied with a look at Sam that said he wasn't an idiot.

"Fair point. But we should really do something about the colour blindness." Sam replied as they started out of the room and down the corridor.

"How would you fix something like this?" Cas asked.

"I've read that there are contact lenses that help some people." Sam said. Dean gave him a weird look. "What?"

"Where the hell did you read that?" he asked, voicing his question.

"The internet, I was bored and we weren't on a hunt." Sam said as he pushed open the door to the building.

They left quietly and walked down an alley where they had left the impala.

"How do we get him some?"

"They sell them on the internet." Sam replied as they got in the car.

"Do I get a say in this?"

"Sorry Cas, but it's not just your life at stake here, were getting you the lenses. Besides you'll get to see some colours for the first time." Dean said as he revved the engine.

When they got to the cheap motel Sam fired up his laptop and found a site that sold the lenses. They ordered the lenses and said that they were at their nearest drop box. They paid for their room and left the motel, starting to the place it had been sent.

When they got there it was dark. They all decided that they needed some sleep so they slept in the car.

Dean woke up to a rapping on the window.

"Are you Sam Jagger?"

"I'm his brother, he's asleep. I'll take them though." he replied as he wound down the window. The post man nodded and handed him the small package before continuing down the road. Dean leant over the back of the seat and poked Cas until he woke up.

"They're here, put them in. Honestly I'm amazed they were that quick." Dean said with a smile as he handed the box to Cas who opened it cautiously.

"How do I put them in?" he asked, looking a the cases which he thought were red and green but looked yellow and grey.

"Put one on you finger, open your eye wide, then put it on your eye."

"On my eye?"

"Yes on your eye."

Cas took one of the contact lenses out of the case and rested it on his finger before opening his eye wide.

"Like this?"

"Yep, now put the contact in."

Cas pressed the contact lens to his eye and turned his blue eyes to look at the thing, the contact lens falling over his pupil. He did the same with the other and looked around the car.

"Wow."

"How is it?" Dean asked with a smile at the sight of the look of awe on his face.

"It's amazing. There's so much colour. I've never seen this much colou- wow, your eyes are a lovely green." Cas changed his sentence part way through. Dean smiled, his cheeks colouring pink.

"Thanks. Hey at least you won't get us killed."

"Which is a good thing. I now see that the shirt is red and green. Your eyes are a nicer green though."

"Thanks. Hey, those are monthly, they'll last a month before you have to change to a different pair. You have to take them out before you go to sleep though or else your eyes will kill you."

"How can my eyes ki- oh its a term. You seem to know a lot about contact lenses Dean."

"I wore them when I was younger, I hated the idea of glasses, they were so inconvenient. You could probably pull glasses of though. It would go with the nerd look." Dean said with a smile as Cas continued to look around the car, taking in the different colours.

"This is so cool. You have advanced so much in the past century."

"Yeah, we have haven't we."