Literally just had the idea a minute ago, so I'm going to write it.

Basically UKUS

pirate!englandxmerman!alfred au

(Alfred is not a country, he's a merman. Also, no family ties so it's not incest)

(Also, there is smut and Alfred is 16 while England is 20)

_________________________________________________________

The British Empire was the terror of the seven seas. He was a conquerer of ships, taker of treasures, and commander of the waves. He was a pirate of his own league and unmatched by any other. 

Arthur Kirkland was the king of the world. He had all the gold he could ever imagine. But still, as he sat in his cabin staring at the ceiling, he felt empty. He felt like he was missing something as he stared out of the small window into the brisk night. Finally brushing the emptiness off, he readied himself for bed. He dressed in his normal nightie and laid in his large bed, covered in the most expensive silks and velvets. The bed was large, yet England slept alone. That's when he heard it, the playful splashing and angelic laughter. He instantly stood from his bed and peeked out the window, gazing at the glorious image every pirate dreams of. 

He saw a mermaid, well merman to be technical. He was gorgeous! His eyes were glittering like sapphires and were speckled with stars. His hair was golden like all the coins Arthur had stored from his many conquers. His skin was kissed by the sun with passion, the tan the merman possessed could melt the entire artic. His smile was whiter than the rarest ivory pearl and he had the sweetest dimples. Lastly was his tail, it was a work of art.

Arthur drooled at the merman, who was playing with a bunch of dolphins. The stranger's body was so lean, yet so muscular. Then and there, England made up his mind. He had to have the merman for himself. He quietly crept around the sleeping ship, getting to the main deck. He swiftly tossed over his thinnest netting, so that the merman would never see it coming. Arthur then waiting on the side, ready for the moment the blonde beauty would swim right into his trap. Well, it didn't take long. The merman was swimming happily when his tailfin got caught in the razor netting. Trying to free himself, he ended up getting more tangled. Arthur finally pulled him up and the scared boy plopped in front of him.

Arthur smirked down at him, but then realized how terrified the boy was. He then noticed how the razor netting cut along the boy's tail and skin, making him bleed in every slash. Arthur felt awful and treated his wounds in silence. Arthur then picked him up bridal style and sat him on the edge, allowing the boy to swim free. He sighed as he watched him go, the beautiful merman diving into the depths of the sea.

Months passed and Arthur never forgot about him. On the night of Christmas, he threw a party for his crew. They all drank happily, unaware that they were sailing towards a huge rock. Well, they certainly felt the rock. The ship jolted to a stop and began to sink, so Arthur quickly directed his crew to the lifeboats. He was so busy helping his crew that he didn't even notice the shadowy figure watching him from behind the rocks. Once he was sure his entire crew was safe aboard the lifeboats, he ran to them. But, his foot got caught in a piece of a broken floorboard. Arthur yelled for his crew to help, but they all just smirked and dropped the lifeboat, rowing happily away. England was furious at the betrayal as his ship completely sank, his head quickly submerged. He was cutting in and out, the last thing he saw was a black figure swimming right at him. 

He awoke in a small cabin in his colonies, where he smelt soup cooking and heard wonderful singing. He finally cracked open his eyes and saw familiar blonde hair and those amazing crystal eyes. 

"Where the bloody hell am I?" Arthur croaked. That got the other teen's attention quickly, and he hurriedly gathered a bowl of stew.

"My secret cabin on the coast," the boy sat next to him and held out the spoon, "open wide," he smiled. Arthur did as told and swallowed the divine liquid, "you gave me quite a scare, Iggy,"

"Who are you? Why did you call me that?" Arthur spat with venom. His eyes softened though as the boy didn't even flinch. The boy wasn't scared of his tone.

"You recognize me, don't you?" the boy asked playfully. Arthur looked down to see the boy had legs.

"You don't have-"

"I know, it disappears when I go on land. I've been watching you for a while on my nightly swims. Ever since you healed my wounds. My name is Alfred, and I wanna call you Iggy," Alfred finished feeding Arthur and got up. Arthur looked at Alfred's ass and licked his lips. The boy couldn't be any more than 16. Arthur smirked and wondered if merpeople biology was the same as nation biology. If mermen could have babies, Arthur wanted Alfred to have all his children.

"You're so beautiful, Alfred," Arthur whispered as he sat up. Alfred turned his head cutely.

"Did you say something?" he asked sweetly. Arthur stood up quickly and walked over to Alfred. Alfred was a little intimidated so he continued to back up until he hit his wall. England loomed over the former.

"I want you to repay me with your body and soul," England's hot breath blew onto Alfred's ear, "I want you to bare me a son. I want you to be my wife," England sweetly bit Alfred's ear lobe. The younger moaned sweetly and clutched Englands shirt.

"Does that mean that you love me, Iggy?" Alfred asked innocently. England bit down on Alfred's neck, making the younger yelp in pleasure, "I-I'll take that at a yes," Alfred whispered as England abandoned the hickey and smashed their lips together.

SMUT UNTIL THE END

Alfred couldn't feel his legs, they turned to jelly as England proceeded to get rougher and rougher. The empire then picked up Alfred and carried him to the cabin's bedroom, laying the younger down gently. England ripped off the former's clothing and tossed it carelessly on the floor. England passionately kissed Alfred roughly, licking the bottom lip and asking for entrance. Alfred happily complied and allowed England to claim his entire mouth. When the two finally separated, England had Alfred suck his fingers so he could properly prepare him. Once that was done, England entered two digits into Alfred's entrance as they kissed sweetly. Alfred's dick began to leak precum and England dick became solid with a painful erection. As they kissed, England decided to use his free hand to tweak Alfred's nipples, making a muffled pleasured scream come from Alfred. England finally stopped kissing Alfred, allowing the younger to breathe before he let his erection loose.

"God, I have never seen such a rare beauty like you, Alfred. The thought of you swollen with my children makes me so happy," England gently pecked Alfred's lips as he aligned himself, "I'm going in," he whispered as he slowly entered. Alfred yelled in pain and tears sprung from his eyes. England let him adjust, wiping his tears sweetly.

"It...Hurts..."

"Just give it time, it will feel nice soon," England slowly began to pump himself inside of Alfred. The younger clawed at the empire's back as his legs began to tremble. It took a few minutes, but the pain did melt away.

"Ahhhh~ Iggy~" Alfred moaned sweetly. England bit his lips and went deeper. The thrust became faster and America smiled, "Iggy! I love you!" England loved hearing Alfred moan. It was intoxicating. He thrusted hard in one place in particular, "AH~ THERE~" England smirked and continued to thrust there, beginning to pant.

"God, this is Heaven!" Arthur thrusted harder as he felt himself nearing release. He saw Alfred was as well, so he continued to hit the prostate as hard as he could. The two felt hot and sweaty as the bed began to shake.

"IGGY~ I'M SO CLOSE~" Alfred panted. Arthur nodded and clasped his hands onto Alfred's.

"Let's cum together~" Arthur finally thrusted his fastest, both of the climaxing at the same time. Alfred's gut began to swell a little bit with Arthur's large load of semen. The two collapsed, still panting roughly.

"That was amazing, Iggy~" Alfred cuddled into Arthur. Arthur smirked and lifted Alfred thigh, penetrating him again.

"That was only round one," the pirate slyly whispered as they continued.

Five rounds later and Alfred's gut was completely bloated from Arthur's cum. Arthur gently grazed the bloated belly.

"Iggy, I think you gave me enough cum for ten children," Alfred commented quietly. Arthur kissed the bloated belly.

"Yeah, you are right my love. Now, I think it's best if we rest," Arthur covered them up and cuddled Alfred close.

Nine months later, Alfred gave birth to three beautiful children. Arthur felt happy now.

He finally found out what he was missing, a family.