Dean was exhausted. Of course he was. He'd been tossing and turning all night long. He tried to blame it on their last mission. All they did was fucking fight. Couldn't the demons, witches, werewolves, and whatever the hell else there was, leave him alone? He thrashed about in bed, knowing it was ridiculous. He needed the adrenaline of taking the bastards down. He couldn't live the "normal life". It was overrated anyway. Married, 2.5 kids, white picket fence, some ugly dog running around. Dull, repetitive. He needed adventure.

"Dean."

"Holy shit, Cas!"

Cas had popped up right in front of him, standing on the other side of the bed.

"I am sorry, I did not mean to frighten you," Cas said.

"It's fine, but damn, dude, you got to work on personal space. What are you doing here? It's the middle of the night, I was sleeping," Dean said.

"It is actually well past the middle of the night. And you were not sleeping, I saw you fidgeting," Cas answered.

"Yeah, okay, I'll give you that. Is everything okay?" Dean asked.

"I don't know. I have this strange sensation in my stomach. And I did not eat, so I cannot be about to be sick. I am quite worried," Cas said.

"Guys, this is fascinating, but could you shut up?" Sam's muffled voice came from the other bed.

"Oh, good morning, Sam," Cas said politely.

"It's not morning, it's six a.m.," Sam said, rolling over.

Cas watched him resume snoring, and turned his gaze back to Dean.

"Please, Dean, there is something wrong," he said.

Dean sighed. Ever since Cas' stint as a human, any illness at all was freaking him out. He didn't know why; Cas was mostly angel again. It's not like a stomach bug was going to kill him.

"Fine. Let's go for a walk, okay? That way princess Sammy can get her beauty sleep."

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Dean had thrown on a jacket over his pajamas, and soon found himself wishing he had dressed warmer. It was cold to be May. Together, he and Cas walked down the street from the shabby motel Sam and Dean were staying at, stopping at a rather ugly grassy area with one park bench that the town had boldly labeled Town Park.

"So how have you been? We haven't seen you in a few weeks," Dean asked.

"It has been busy in Heaven. I am getting readjusted to my Grace, and it has mostly returned," Cas answered.

"Well, at least you can fly and pop in where you want to now. How's the healing?" Dean said.

"I have not had the chance to test it, not being with you and Sam. And I have not felt much like it, especially when the stomach pain began," Cas said.

"Geez, how long has the pain been going on?" Dean asked him.

"It started the day after I returned to Heaven. The curious thing is, I feel fine now, though I do fear its return. It is…most uncomfortable. I feel like I will be sick, but that's impossible. It aches so badly I sometimes feel it in my chest. My mind feels strange too, like I cannot keep concentrated on my duties in Heaven. Is this serious?" Cas turned his big blue eyes to Dean.

"It doesn't sound very serious to me…you said it started after you went back, but you feel fine now?" Dean furrowed his brow.

Cas nodded.

Dean knew this feeling. It kept him up at night. It started when Cas left, and continued since then. He felt like he'd lost a part of himself when Cas returned to Heaven. He found the loss of his best friend very hard to take. Of course Cas wouldn't know what it felt like, since he had only recently begun to feel things like this.

"Cas, buddy, you're lonely," Dean said softly.

"Lonely? But I was surrounded by my brethren. How could I be feeling alone?" Cas wondered.

"Sometimes, you can be lonely when you miss a person. It doesn't matter if someone else is there with you or not, even if it's family. You just want to see that one person again," Dean said.

"You have felt like this before too?" Cas asked him.

"Of course. Do you know who you were missing?" Dean said.

"Well, given that I am feeling fine now, and Sam is not with us, I would say it was you. Did you miss me too?" Cas said.

Damn. Dean wasn't good with this kind of talking. Sam usually did this kind of thing. But he was certain he had missed Cas. He didn't realize he'd become so used to having him around all the time.

"I missed you too. And I'll miss you when you go back to Heaven, but I know you have to," Dean answered truthfully.

"I have been thinking about that. If missing you is causing me pain, I don't want to go back."

Dean looked up quickly.

"You have to, Cas. You just got your mojo back. Angels can't live on Earth all the time," Dean said.

"You said you would miss me. And I would miss you. Besides, Dean, I am afraid my 'mojo' is not returning at the rate I expected. I fear I may be becoming human again," Cas replied.

"Cas, that's stupid. You just got it back, why would it be leaving again? You haven't sinned. You're just worried about getting sick, but you're fine now. You're here with us, and you can stay a few days to help with the loneliness, then go back to do your job. Come and visit whenever you get lonely," Dean said.

Cas nodded. Suddenly, he reached over and took Dean's hand.

"You said you missed me too. Why?"

"I don't know, man, I got used to having you around," Dean said, pulling his hand away. Damn, the angel really needed to learn boundaries.

"I know it is customary for humans to miss those they love," Cas said, tilting his head.

Dean nearly choked.

"Dude! I mean, I missed you, we're best friends, but we're not picking out curtains together or anything," Dean said.

"Why would we need curtains? You mainly stay in motels. They already have curtains," Cas looked confused.

"Just-just forget it, Cas. I missed you, leave it at that. Come on, let's go wake up Sam and get some breakfast."

The pair walked quietly back to the motel room, Dean's thoughts swirling in his mind.

What did Cas mean about humans missing those they loved? Well, Cas spoke plainly, so he meant what he said…but what kind of love? Like brotherly? Or something else? There was no denying Dean had missed Cas. Sam had called Dean out on "sulking" several times since Cas left. But wasn't it normal to miss your best friend? Yeah, yeah. Of course it was.

Dean contented himself with those thoughts, until another one jumped quickly to the front of his mind.

Why had his heart jumped when Cas had grabbed his hand?