4.
The fifth time he barely makes it into the elevator before the doors close, and then Castiel says "Hello, Dean" and he almost jumps right back out.
"Hey…Castiel," Dean mutters , "You trying to kill me?"
"I did not mean to cause you any harm," is Castiel's honest answer, and a bit of worry has made its way into his frown.
His tie is still crooked, but Dean can't do anything but keep himself from glaring at it. He tries to think about his article about pre 2000 muscle cars, which makes him think of his beloved Impala and that works long enough for him not to make a fool of himself.
5.
The seventh time Dean croaks hoarsely, "Your…" and then he drops it and tries to cover up his words with a cough. Castiel tips his head to the side, like a lost little puppy, but doesn't say anything.
6.
The tenth time Castiel isn't wearing his trench coat. His tie however is as sad a view as ever. Dean has to tear his eyes away from the little crinkles where the fabric is all twisted and turned.
"Getting warmer outside, huh."
Castiel's disturbingly breathtaking eyes light up with the hint of a smile when he says, "Yes. I saw a bee today, in my sunflowers."
Generally, Dean thinks himself a pretty level headed, normal, decidedly unromantic guy. Apparently Castiel and bees are an exception. There may or may not be a funny feeling in Dean's stomach when he gets out at the tenth floor that day. It's hard to write about cars when he can't stop thinking about Castiel.
7.
After two weeks he interrupts Castiel midsentence to grab his tie and forcefully straighten it. Castiel's eyes widen in a way that would be comical if it wasn't so cute, and a blush taints his cheeks. "I don't understand the whole – I'm not very good at – " he stutters while Dean tightens the blue silk so that it fits snugly around Castiel's neck. They don't break the eye contact once, Dean can almost feel Castiel's breath.
As soon as he is content Dean steps back, the doors open with a bing and he can escape out into the hallway, leaving behind a thoroughly flustered Castiel.
Consequently Dean takes the stairs the next week.
He also works out more after he considers that depending on how his and Cas' next encounter goes he might just have to take the stairs for the rest of his life.