There was a splash as Sam scrambled away from the wave, followed by an obnoxious burst of laughter from his brother, who was standing further up on the beach. They had just been arguing, minutes ago about whether the waves would come up this high on the sand, and Dean, insisting that they would, had just won (and obviously the payment for him being right had been Sam's double soaker).

The Winchesters had come to California for a particularly strange case, which sounded like a possible demonic possession. On this beach, a teenager had decapitated several people; with a surfboard.

"You know, it's been forever since we've taken a trip like this," Dean said, still grinning at his younger sibling. "Did Dad ever even take us to the beach...?"

Taking off his soaked shoes and socks, Sam looked up, thinking back. "Yeah. Well, technically. That one time, when we went to Florida in '90; how old were you... Eleven? Anyways he took us to go check out that cursed object case. We went without him knowing. But it was rainy and cold and the middle of October, so I wouldn't go swimming."

"Oh yeah!" Dean laughed, "We snuck away while he was out interrogating. You sat there and complained with a hotel towel over your head the whole time I swam... Didn't I lose my boxers?"

Sam made a face, "Yeah, you did... And you were sitting beside me on the beach complaining at the end of the day too."

Dean frowned, trying to remember more on the topic as he sidestepped to avoid another wave.

They had walked almost the entire way across the beach, to one of the victims' mother's house when a strong hand grasped Dean's shoulder. He whirled around, his hand already resting on his gun, but visibly relaxed when he realized who it had been.

"Cas, I've told you a hundred times man, don't sneak up on me..." He felt his heart rate steady, and he dropped his hand back down at his side.

The angel-gone-human looked extremely distressed, and he began walking briskly in the opposite direction, his long grey suit-jacket overcoat swirling and billowing around his ankles. Dean ran after him, just catching the end of his sentence. "-thing doing this is not just any demon."

"Hang on; Cas what the hell is going on? What are you talking about?" Dean said, trying to stay calm. If Castiel was worried about this thing, it was definitely worse than they'd thought.

He turned around, staring Dean directly in the eyes. "You should go." His gaze was intense, and it was becoming harder for the human to return it.

Sam jogged up to them, looking confused. "What's up Cas?" He glanced briefly at Dean, an unidentifiable look on his face, before turning back to Cas and asking, "How did you find us?"

"It wasn't intentional. You both need to leave; now. I'll take care of this."

"No Cas-"

"Dean." Cas cut him off angrily, sending him a glare that clearly said, 'back off'.

Sighing, Dean lowered his head and ran a hand through his hair. "Sam, give us a minute."

The younger Winchester nodded, and began to walk further up the beach. Dean waited until his brother was a fair distance from them, and then whirled around to face Cas. "Are you mental?! Dude, you're human now, just like Sammy and I; you can't just go around hunting these things and pretending you know what you're doing. You're gonna get yourself killed!" He began pacing back and forth, feeling his shoes sink into the soft sand. "Why can't you just let us help you? Let me help you... I mean the amount of shit we've gone up against... We faced fucking Lucifer; what could be more dangerous than that?!"

"Dean, it's not about that." Cas said, quietly but firmly, his brow knitting together as he frowned slightly. "I just want to do this one thing on my own. I-I need to do some good to make up for... My most recent actions, as they can't be undone..." He trailed off.

Dean hesitated a moment before replying, "I understand how you feel. But Cas, you gotta be more careful. Call us if you're gonna do something crazy like this, geez..." He sat down on the sand wearily, folding his arms across his knees. "Just... Learn how to ask for help, okay?"

"I'll try, Dean."

There was a long silence as the two men stared out across the vast ocean. It was a pleasant silence, filled with the calming sound of waves and the odd seagull cry.

The first to break the silence was Dean, who said, "So uh, what is this thing anyways?" He looked up at the fallen angel, and studied his blank expression carefully. His face had fallen slightly after Dean had brought up the case, but otherwise had remained as stoic and unreadable as ever. "Demon? Something new maybe?"

With a small sigh of resignation, Castiel replied, "It's a type of demon, yes. This particular one likes to travel through the water to possess humans. It's..." He looked up for a moment, evidently trying to find the right words to describe it.

"Like a leviathan-demon hybrid?" Dean offered with a grimace. He hated the thought of something like that existing. If the thing ever got into the water supply...

Cas' gaze fell on Dean again as he nodded slowly and said, "Yes. Sort of like that. Though it's very rare and it also, apparently doesn't devour its victims."

"Well that's a plus..." Dean grunted.

"There's hardly any information or lore on it at all. I spent two days researching, and even with my extensive knowledge of the supernatural, I don't know too much about it." Cas added, finally sitting down on the beach beside Dean and smoothing out his suit.

Dean shrugged. "If we can find the son of a bitch, we can exorcise it. That's all I can think of right now. Do you have anywhere to stay tonight?"

Cas shook his head sheepishly. "No, I figured I would find a shelter, or an alley to sleep in. It's not as bad as you think."

"Sammy and I already booked a room. When we're done here, you can come stay with us. We'll figure something out." Dean said, standing up and brushing off his pants. He glanced over at Sam standing in the water up to his ankles, holding his shoes in his left hand and his pant legs in his right.

"Dean, no I-"

He held out his hand to Cas to help him up. "I'm not taking no for an answer. Come on, Sam's starting to look like he's stuck in one of those cheesy romantic chick flicks."