A/N based off the tumblr post, added as a picture. Hope you enjoy :)
It was another night, Cas was sleeping and Dean sat in a chair next to his bed. Dean had made sure Cas was asleep before he came in. he knew Cas was a heavy sleeper. He waited till Cas' breathing was evened out.
Once he was sure Cas was fast asleep, he ran his fingers through Cas' hair. It was so, so soft.
"Cas," he murmured. "You have no idea how happy I'm with you. I just... I can't tell you when you're awake. I'm sorry." He thought about what Cas had done for him, how he had saved Dean's life every time. And Dean just couldn't tell him.
He couldn't open up to people, not even Sam or Cas. "You make me so happy, Cas. You don't even notice, do you?"
"And look at you, lying here. So adorable, so... beautiful. If only you could see it yourself. If only you realized how grateful I am to have you, how much I care for you. If only I had the guts to tell you when you're awake." Dean sighed.
He closed his eyes and pressed a kiss that was barely there on Cas' cheek. He went on, and kissed Cas' other cheek, his brows, his forehead and finally his lips.
"I love you," he whispered. He traced his fingers slowly from Cas' jaw to his neck. "I love you so much."
Suddenly, he felt Cas' pulse triple against his fingertips. Dean slowly opened his eyes to see Cas' awe struck expression.
"Oh shit," Dean cursed. Cas wasn't supposed to be awake. "Cas I'm so sorry, I didn't... I..."
"Dean," Cas said. Dean didn't say anything as he got up, causing the chair to fall as he nearly tripped over it. He wanted to leave, right now.
"Dean stop," Cas said again.
Dean stopped. "You don't have to say anything, I just... I don't know." He was starting to leave again.
"Dean, I said stop," Cas said, now commanding Dean.
Dean didn't stop this time. He didn't want to hear what Cas had to say. He didn't want to hear Cas tell him how much of an idiot he was.
Dean was afraid, afraid he could never talk to Cas ever again, without being reminded of this. He wished he had never done this. He should've just stayed out of Cas room.
He should've never even start telling Cas what he feels. Dean Winchester doesn't do feelings. And he surely doesn't do feelings with his best friend while he sleeps. It made him look like a creeper.
He's been in Cas room so many times. The first few times he didn't even say anything, afraid Cas would wake up. But Cas didn't.
So after a few times, Dean started talking. Started telling Cas things. Things he'd never say out loud to Cas. Things Cas shouldn't even know.
When Dean accidentally touched Cas' cheek once, Cas didn't flinch, didn't wake up. Cas was a really heavy sleeper.
And since that moment, Dean couldn't stay away. He had to go. He had to tell Cas what he felt, or it would eat him from the inside.
But now Cas had been awake. That had never been part of the plan, and Dean felt guilty all over. He should've never started this. He should've left Cas asleep, and bring his unwanted thoughts and feelings somewhere else.
He should've-
"I love you too, Dean."
Dean paused and slowly turned around. He didn't say anything.
"That was the sweetest thing you've ever said, and even if I wasn't supposed to hear it, I'm glad I did." Cas said, looking at Dean.
Dean still didn't say anything, he hadn't even moved yet.
Cas got out of bed and walked over to Dean, his hair messier than usual, a slight blush from when he was sleeping, looking cuter than ever. He waited a moment before pulling Dean into a hug.
"I love you too," he whispered, as he felt Dean's arms wrap around him.