Whe the clock strikes 12

"Are you mad, 'Nea?"

"What part of 'try to stay under the radar' equates to befriending the crown Prince?"

I'm feeling a Cinderella -esque situation where there's been a search warrant out for Prompto from the moment he was stolen from the labs.

And if everyone is looking for a blonde boy, then theres one way around that. 

Maybe in this instance there weren't a lot of clones - maybe Prompto is the one and only successful one and that makes him very valuable. 

Aranea was the one who smuggled him out and they laid low in Niflheim for a few years before she brought him to Lucis, a little blonde girl. Maybe every child was being checked at the ports but they were foolishly only checking boys.  

Aranea gets them fake papers when they get to Lucis and they set themselves up in the slums in Insomnia. Prompto doesn't dress up when it's just the 2 of them, wanders around the house wig-free. He also just plays the flat as a board card as a girl rather than messing with bras - its just easier.

He meets Noctis when he goes to highschool.

I feel like Aranea has probably trained Prompto so that in the event of anything happening to her he would be able to defend himself and survive. Maybe he gets teamed up with Noct on an assignment and Noct's a bit hearteyes for him.

Blondes.

So then there's the matter of Noct's upcoming coronation. His father in a gesture of goodwill offers him a time to choose someone for himself to marry, if he doesn't find someone by a certain date then it will default to Lunafreya.

Noct isn't actually that bothered and even asks why they need to do that - he gets along with Lunafreya, it was far from the worst match, but his father wants him to at least have the opportunity to find someone he finds a connection with himself.

So he arranges a grand ball, all are welcome. The other countries can send representatives if they want. 

Aranea thinks it's a terrible idea. Theres going to be people from Niflheim there but I imagine by this point Noctis and Prompto are pretty good friends. Prompto kicks his ass at video games so maybe he and Aranea have a fight the night of the ball and she tried to keep him away but he sneaks out and yep sparks fly.

And bullets.