When the thought finally occurs to Dean, it takes him about five seconds to decide to keep the information completely to himself.
Realizing you're in love with a celestial being in the form of a human man's body isn't exactly the type of news you want broadcasted. Especially when you've never identified as liking men. Or, you know, other supernatural species without specific gender.
He figured it could be his little secret, vowing to deal with the confusing and inconvenient feelings later, when the world isn't constantly trying to end itself.
This would have been a great plan, a perfect plan; if it hadn't been for one tiny, little detail. Castiel just so happened to have a certain addiction to spying on Dean's dreams.
So when Castiel decides to show up in Dean's room after he's hit the hay and he lightly touches his fingertip to the man's forehead, he's a bit surprised from the nature and content of Dean's dream, a dream no longer contained and burdened by his past ignorance towards his feelings for the angel.
It's not like Cas has never cropped up in Dean's dreams before, but when Cas witnesses Dean pulling the angel in for a passionate, totally unexpected kiss inside his head, his finger slips off of Dean's skin and he finds it hard to catch his breath.
Castiel has always had feelings for Dean. One look at his righteous, self-sacrificing soul and Cas was a goner for good.
That probably explained the nearly blinding excitement that overtook him after his brief look in Dean's head.
What Castiel did next probably wasn't the most thought out, or even a good idea considering the gun Dean keeps under his pillow, but he was more than impatient from watching this addictive and frustrating man constantly look for temporary love in the bars and dives he frequented so often when Castiel was right there, a permanent, more than willing fixture.
Nevertheless, Cas met Dean's unconscious lips with a needy gasp and without hesitation. Dean's breath instantly caught in his throat mid-intake and his eyes popped open to search out who had attacked his face in sleep.
For a split second, he thought he was still asleep, finding the same scene before him. But it was just too real as Castiel backed up a few inches and searched Dean's face, a happy radiance showing in his eyes. He had a very mischievous smile tingeing his lips that made Dean decide now was not the time for wasting precious moments on words.
He framed Castiel's face with both of his hands, pulling the angel in again, pressing his wide smile to his lips.
Now, Dean hadn't forgotten Cas' certain innocence when it came to things of a sexual nature. He was determined to save those intimacies past kissing for another night, wanting Castiel to enjoy and acclimate to each new experience without feeling rushed.
It was a sweet affection brought on by good intentions and Dean kept his hands from roaming Castiel's body even though they were itching to do just that.
What Dean didn't prepare for was Cas' reaction. Upon their second lip locking, Cas became unhinged; his hands roamed Dean's body freely and elicited involuntary responses in it with very little effort. Cas began whispering enochian words into Dean's ear, his shoulder, his neck until Dean couldn't take it anymore. His hands released their hold in Castiel's hair and began exploring Cas' body with the same rushed impatience.
Whispered words in the English Dean could understand took all hesitation from his mind: "Now, Dean." With that he pushed Cas' trench coat and jacket off of his shoulders and began unbuttoning his shirt buttons.
Castiel, not straddling Dean on top of the bed, rolled onto his back, pulling Dean with him until their position was reversed. His finesse was incredible considering his lack of experience.
Dean finally finished the buttons of the dress shirt and helped Cas wriggle out of it beneath him. The sight of Cas' bare chest nearly knocked the breath out of him and Castiel was hard-pressed to get him to stop pressing soft kisses to the skin of his chest and stomach.
Cas tugged at the hem of Dean's t-shirt, pulling it over his head and breaking them apart for a breathless moment. Now it was Cas' turn to feel overwhelmed as his fingers sought out every crevice and curve of Dean's torso.
Their lips met again, their tongues almost fighting as their lips formed silent words of affection and pleasure. Dean pressed the growing pressure in his boxer shorts against Castiel's thigh, feeling more and more tension climb his back and more and more heat flood his body.
Watching humanity for millennium had to have had some sort of effect on him after all because there was no hesitation before Cas reached a hand to grasp the growing hardness in Dean's pants. Dean's breath came short and a whimper rose to his lips, pausing their wrestling mouths.
The sound elicited a similar reaction in Castiel's pants and suddenly he had to get them off. Once again he gripped Dean's shoulders and rotated their position, putting Dean under him. He shimmied his constrictive pants off, leaving only two pairs of boxers between them, the lack of fabric somehow making the room infinitely hotter on their sensitive skin.
In most cases, Dean would be unsatisfied with his current position, but the possessive aggressiveness that lit up Castiel's eyes as he stared down at Dean sent all the words from his mind and made him ache for domination.
Cas moved to place one leg between both of Dean's and slowly, after linking their mouths back together, began grinding their hips together with a very slow rhythm that had Dean writhing in mere moments, nothing more than friction driving him crazy. His nails clawed at Cas' back, his mouth uttering nonsense phrases around Cas' lips. "Cas, please. Don't-. Cas, don't stop. Shit, I-." Cas' breath came shallower and shorter, the pleasure building in the pit of his stomach, forcing him to speed the rhythm up a bit.
Their faces had to break apart, the enochian and whispers and heavy breathing leaving little room for busy lips.
Their names were both called out by the other as the building excitement reached its climax between them, leaving a mess they'd clean up later.
Castiel collapsed on Dean's chest, the act taking away a surprising amount of his energy – even as an angel.
Dean's fingers rubbed soothing circles on his back while their breathing slowed. He murmured sweet promises in Cas' ear, Cas' breath hot against his neck.
So it's safe to say Dean kinda sucks at the whole keeping-secrets-from-Cas thing. He's learned his lesson, at least. Now he just whispers any secret he can come up with into Cas' sensitive ears.