Tale as old as time
They had been through this before. The same fights, the same drama, the same nonsensical bullshit that wrapped around the perimeter of their relationship. Nico and Percy had been in a constant loop of yelling and screaming for the last two weeks, though both of them didn't remember what the original fight was about.
Tune as old as song
After three years together, they'd be expected to be used to petty, typical couple fights. They weren't. They still were baffled at the fact that they fought over the stupidest, most pointless things possible. Like what show to watch, where to place your shoes, who gets what side of the bed, when to set the alarm to and what creamer to get for their coffee.
Bittersweet and strange
They weren't used to fighting. It was terrible to them, honestly. Nico hated seeing Percy so fiercely angry with him; Percy tried with all of his might not to die of fright when Nico's anger was directed towards him. But it brought them closer. It always brought them closer.
Finding you can change
Nico and Percy were, quite literally, polar opposites. Nico was dark while Percy was light, Nico was brooding while Percy was optimistic. Nico was one to hide in the shadows and just stay to himself, the way he(and most everyone around him) liked it. Percy was the social butterfly, never to be missed at any gathering of any sort, no matter what was going on.
Learning you were wrong
Nico gave up on trying to be like Percy. Percy loved him for him, and he was going to act how he wanted, because that was him. Percy didn't want to be like Nico, all dark and hating life, but that never took away his love for him.
Certain as the sun rising in the east
Percy, though being betrayed by Nico many times, had never doubted Nico's feelings for him. It, however, took Nico some time to get used to the fact that he was Percy's and Percy was his. He never doubted for a second, though, that Percy and him were made for each other. Like two different storms.
Tale as old as time
Every fight made them stronger. Every fight made them know that this is what they wanted. They wanted the fights, the endless bickering that made them so unbelievably irritated.
Song as old as rhyme
Nico knew no matter how many times they ran into a problem, they'd conquer it. He was Nico fucking di Angelo and his god damned boyfriend was Percy fucking Jackson. Percy Jackson never loses anything, especially when Nico di Angelo is right next to him.
Beauty and the beast