Castiel had seen many "Valentine's Days."
Well, actually, he'd seen them all. He'd just never spent one with anybody. Not that he had anyone to spend it with.
Which he didn't care about. Not at all. Nope. He had no lover, so he would have no valentine. It was very simple.
So he didn't care when Dean went out and came back with a girl.
"Picking up chicks," as Dean called it, was a frequent habit of his and he really shouldn't expect anything less.
Castiel spent Valentine's Day the way he always did—watching humanity. But not Dean. Dean could look after himself.
Castiel saw a couple get back together after a long fight. They hugged, cried, and promised never to fight again. ("They'll be back like this in a month," the couple's cat said to Castiel.
"Believe in them," Castiel replied, who thought everyone deserved some happiness.
"I think they get pleasure from it," the cat told him. They might. Humans were fickle. Castiel knew all the different types of unhealthy relationships. He watched and took note.)
Two friends were sitting on a park bench. The names of the two were Matt and Jerry (this wasn't really important, but Castiel took note of the names of people he watched). They were both single and bemoaning this fact. Jerry asked Matt why he was so annoyed with being single when he had dumped his girlfriend just a week ago and Matt avoided answering by asking why Jerry never had a girlfriend at all. Eventually Jerry admitted his love for Matt, and the two friends kissed. A nearby dog quietly barked, "Finally."
And Castiel left to go on to the next couple.
After a day of watching humans express their love, he felt strangely depressed. It was a curious sensation because Castiel was sure he'd never gotten upset over nothing before. The last time he got upset, really upset was because he thought that God didn't care, so he drank a liquor store.
And now he was upset again. It was stupid of him, really.
The only ones who were upset on Valentine's Day are the people who want to be in relationships and Castiel knew how ridiculous that would be. He was an angel. He didn't love. He fought. He obeyed.
(A tiny voice in his head he was beginning to refer to as "But Dean says" told him that he wasn't just another "dick with wings" and that he had free will to do whatever he pleased, even fall in love, but he ignored it because what does Dean know anyways and what gave him the right to haunt Castiel like that?)
The day after Valentine's, he saw Dean.
"So, you do anything yesterday?" Dean asked.
"Nothing I didn't do the day before," Castiel replied, and it wasn't a lie.
"I guess angels are to busy to go out on a date and stuff," Dean shrugged, "But you must have seen like, what? All Valentine's Days? And you were single for all of them?" Castiel nodded. "That's a bit sad, Cas."
"If you wanted to go somewhere with me, all you had to do was ask," Castiel told Dean. The angel wondered if the human would consider this as a sort of awkward flirtation of a man who had never asked someone out on a date, never wanted to, not really, but changed his mind because he met someone that was just so—
Dean didn't respond. He looked at Castiel curiously and then Sam came in, so they started talking about a hunt.
Privately, Castiel wondered what sort of things Dean and he would have done yesterday if they were dating.