Very few people could miss the way Castiel stared at Dean.
The list went, from least to most common:
3. People who only saw Cas in full badass-mode
2. People who only saw Cas in full angsty-mode
1. Dean
Which was rather impressive - Dean never noticing the looks - seeing as he was almost constantly doing it.
The stare was a fond, longing look, mouth seemingly both upturned and downturned at the same time. Blue eyes looked as though they were staring at the most amazing thing in the world - but something he could never have.
It was rather heartbreaking, really, if you knew the angel.
Most onlookers just thought Cas was a friend of Dean's, who had a major crush on him.
People like Charlie, and especially Sam, knew different.
Dean's best friend, yes, but it wasn't just a crush. The angel had fallen hopelessly in love with the elder Winchester, and - as much as they wanted to - they could never tell the blue eyed man that his human charge felt the same way back. That was up to the hunter to tell him.
After a few years, Dean did eventually get over his whole 'I'm 100% straight' thing, and admitted to himself he was in love with the trench-coated angel. It took three months before he admitted it to Sam and Charlie, and another three to admit it to the angel himself.
Castiel's eyes when Dean admitted his feelings shined as though he had just seen the most amazing thing in the world.
Sam wasn't so sure about that, because the kiss that the pair shared - right in the middle of the Bunker's library, right in front of himself and Charlie - was one of the most astonishing sights he'd ever seen.
It must have been their profound bond, still there after all these years.