Written for the Charms Classroom and the Costume Party in Hogwarts (prompt: Merman!AU) and for the Trolley in The Golden Snitch (prompt: "I want to live before I die. It's the only thing that makes sense.").

Surface

Regulus crossed his arms over his chest and turned into the other direction. "No, Sirius! This is a stupid idea and I am not doing it. End of discussion."

"Come on, Reggie! You're no fun!" His older brother swam around him until he could look into his face and did his best seal eyes. "All of my friends are doing it!"

"And if all of them swim towards a smack of jellyfish, you'll follow them, I guess?" he pushed his brother out of the way. "Besides, none of them are the crown prince. You have a duty to the kingdom! You can't just go to the surface! It's dangerous! You might die!"

He started to swim in the direction of their palace, but Sirius quickly caught up with him and blocked his way.

"We can't just sit here and wait for a killer whale! I want to live before I die! It's the only thing that makes any sense! Also, it's not that dangerous; we used to do it all the time as kids! Don't you remember all those times we snuck away and watched the humans travelling on their silly… what were they called again?" Sirius frowned and watched as a school of dolphins passed them. A few of the pups swam a few meters in their direction and did a few loop-de-loops before continuing their journey.

"Ships," Regulus offered hesitatingly, "They are called ships."

"Yes! Exactly!" Sirius twirled around, full of joy. "Don't miss it too?"

"Miss what? The constant lectures from mother and father? The terrible brightness? The trouble to breathe, perhaps?" Regulus snorted. "No, I can't say I miss any of it."

He didn't know what kind of reaction he expected from his brother. Sadness, perhaps. Or maybe anger. But he certainly didn't expect him to start smiling.

"Now I know you're lying!" Sirius declared. "You loved the music of those animals—I think they were called birds? The sound of the waves. And you loved to watch humans do….whatever it is that they do in those odd thing on their ships. You always watched them for hours and only rarely beneath the surface. You're lying and you miss it."

Regulus was stunned. He all the things that his brother had mentioned were but a fading memory in his mind. It had been so long ago.

"Maybe I do," he allowed. "But did you forget that humans eat fish?"

"So do dolphins and tuna. And no one's talking about excluding them in any way," his brother pointed out. "Come on, it'll be fun!"

"Alright," he conceded eventually. "But only because someone needs to make sure you don't accidentally get yourself killed and leave me a the only heir."

"Isn't that always your job?" Sirius grinned as he sped upwards.

"Well someone has to do it!" Regulus yelled as he raced after his brother.

If one considered that it were only a couple of kilometers—around three or so—from the surface, it was quite the eventful journey. Not only did they meet their old, hated teacher, but they also met a blue whale, a floating...something (it was a small object. Round and golden), and Sirius swore he even saw a killer whale in the distance.

Sirius suddenly stopped and pointed over his head. "Is that a human?!"

"Impossible. We're too far from the surface," Regulus quickly denied. Then, however, he followed Sirius glance. "...Holy anemonia, I think it might be!"

Without another second of hesitation, his brother shot forward, towards the possibly human.

"Wait up!" Regulus yelled as he struggled to follow.

Within seconds, they had found the floating human.

"What do we do know?" the younger prince questioned as he observed his brother poking the responseless human.

"I don't think he's breathing," Regulus stated after a few seconds.

"Quick! We need to get him to the surface!"

Each brother grabbed a hand and rushed to the surface, moving their grey tails as fast as they could manage. Regulus didn't even know why he was doing it, and yet he couldn't imagine ever choosing a different option in this situation.

Time passed agonizingly slow, every single second seemed to last longer than the one before.

But then, finally, he felt his head passing from the water into the dry air; joined by his brother and the human in the very same second.

They waited for the human to wake up, but he didn't do anything. After a few seconds, Sirius hit the human's stomach.

Somehow, it worked.

The human's eyes opened and he coughed up some of water.

Once he was done, he started to scan his saviours. He saw their gills and their ears that were eerily similar to the fins of some fish he had seen. He saw their scaled hands and torsos.

Regulus freaked out. Any second now, the human would try to kill him.

Only he didn't. And even odder, his next words were the following. "Thank you for saving my life."

"You're welcome." Sirius smiled at the human. "What were you doing there anyways? I've never seen a human that far down before and based on how you weren't responding it's not good for you."

"My ship, my people abandoned me. They left me to die. They threw me overboard. I swam for a while—I don't know how long—but eventually my strength left me."

"Why would you ever do something like this?" Regulus exclaimed in shocked horror.

The human shrugged.

"Honestly, I don't know. I must have done something they don't like. I'm Remus by the way."

"Regulus," he muttered in response.

His brother on the other hand pulled the human into a hug. "My name is Sirius Black, crown prince of Atlantis."

Remus' eyes almost doubled in size and he began to stutter nonsense, causing Sirius to laugh.

Regulus cleared his throat.

The other two looked at him.

"I hate to destroy the moment here, believe me, but do either of you have any plans how to proceed?"

Going by their expressions, neither had any ideas.

Great.

Please tell me what you think!

~Marvelgeek42