More I think about it, less I understand the… Kidnapping part inspired by the Little Mermaid? I don’t remember that Ariel was kidnapped? But it’s maybe from a next movie that I didn’t see?

So huh… I tried something

Roxas!Merman :

You’re a Princess. A Princess of Heart. And today, many men will come to you to marry you

It became a challenge where every men searched the perfect gift to buy gain your love

One of them came with a merman, a blond pissed one. His tail was a dolphin’s black tail, contrasting with the light color of his hair and his white skin

Maybe it was the first time you saw one, maybe not, but you was attracted by this boy-fish

At first, the merman isn’t friendly at all and you end most of the time soaked

But after a while, seeing you’re not angry at him, he opens up and tell you that his name is Roxas

Days after days, he tells you more about his life in the ocean, about his friends, his life

But… The wedding isn’t far away and you told him that

Roxas can’t do much, stuck into the “pool” and be a merman… But he can’t stay silence

So one day, when you came on the edge of the “pool” he jumps just enough to kiss you and then fall again in the water where he hides himself, with just his eyes out of the surface

First part here !

Note : I’ll take the potion idea from you fanfic idea…! Because then I don’t know what to do. Also, I keep some details out of it to let you imagine the situations

Roxas!merman :

In a way or another, Roxas had been sent back to the ocean but you still was meting him

More the wedding was close, more you was nervous… And more you didn’t want to

Roxas, who was in love with you, asked you in the heat of the moment (after maybe a kiss) that you could be happy with him in the ocean. That you could be together

He’d tell you he just need to see the sorceress/sorcerer to have a potion

But if you accept, you’ll never see your family anymore. Your friends. You will jump into a life you know nothing about beside what Roxas told you without any way back

Roxas promised you he will stay with you and helping you