I added a third (very short) one :)
The third time, it they were eating breakfast. Cas was eating his cheerios, as usual, and Sam, Dean and Kevin were enjoying freshly baked bacon and omelet, made by Cas. Sam had protested and said he would make something himself, especially since Cas wasn't even eating any of it. But Cas had insisted on doing this one thing, as a 'thank you for everything'. Dean moaned when he took his first bite and Sam rolled his eyes, but Cas gave them no mind. Which was weird, because he always looked at Dean a little funny when he made a noise like that. Sam had his suspicions as to why that was.
But anyway, Cas didn't even look up and Sam noticed how he barely ate anything and looked at his cheerios in confusion, like they were to blame for whatever it was that was bothering him. Sam contemplated on saying something about it, but decided against it and continued eating his bacon. Dean may have overreacted a little, but this bacon was really delicious.
After Dean finished his meal (Sam feared he would lick his plate clean. Fortunately, he didn't. But he could tell it was a close call), he finally noticed Cas' brooding. And being the nosey jerk that he wass, he had to know why that was. Jeez, like Cas should be carefree. The guy was a freaking fallen angel. Give him some slack!
"Waddup, Cas?" Cas lifted his head, brows furrowed.
"I was just thinking, Dean. But maybe you could help me."
"Umm ok. Shoot." If possible, Cas looked even more confused.
"I don't want to shoot you Dean. Besides, I'm not even carrying a gun."
"That's not what I- never mind. Just tell me what's bothering you."
"I was just wondering something." Dean nodded, urging him to continue.
"Dean, how can sex be on fire?" Ok. So maybe it wasn't some fallen angel thingy that was bothering him. But Dean would have to clean up the coffee he just spilled. After all, it was his own fault. Sam had to hide a grin when he turned to Cas and answered with the most serious face he could manage:
"Well maybe he can even show you, Cas".
If looks could kill, Sam would be having a nice chat with Death right now. He also knew Dean was going to smash his iPod against the wall.