He hadn't thought it would be like this.
When Lisanna changed his life, it was a huge step for him. Actually being close, being warm to someone. She was his best friend. She became his life when he was young; his everything. He would give his life for her.
When Lucy changed his life, it was just as much of a paradigm shift. She was so different, yet so similar to Lisanna. But her smile was just a bit more learned, showed more suffering that Natsu could empathize with. Lucy became his true comrade, someone he learned to trust with his life.
So he hadn't thought that he'd ever have to choose, until Lisanna returned to her home.
And perhaps that had been his greatest shock, the largest, most dynamic shift in his life since Igneel's disappearance. Lucy and Lisanna, both beautiful, buxom women that were intelligent and caring and perfect; and as much as he tried to ignore the facts, he couldn't.
Natsu was dense, but he was not stupid. They were both in love with him.
The pink-haired dragonslayer put up his regular façade, and refused to face it, because damn it, how could he choose between his best friend and his best friend? When Lisanna had returned, she had become quick friends with the nicer, sweeter-than-the-Edolas-version Lucy.
(He had spent hours just staring at the both of them discreetly, wondering what the hell was happening, what the world had come to.)
Lisanna was flirtatious, and outgoing in the things Lucy was not. The girl was naïve and a die-hard romantic that sweetly flirted and teased gently. She had helped him raise Happy, for crying out loud; surely their ties were not weak, not at all.
Lucy was more down to earth compared to Lisanna; she was just as bright, and an intelligent young woman whose passion was incomparable to all else. They'd become so close that he couldn't imagine life without her.
Without either of them.
So it surprised Natsu when, one day, the two young women pulled him aside outside the guild and asked him to choose.
Because he knew it just as much as they knew it; that they couldn't go on like this, and sooner or later, he would have to choose.
Natsu looked to Lucy; her warm, chocolate orbs, flowing golden hair. The blonde's radiance was there, certainly. She shone as brightly as her spirits. He would give his life for her, he knew that much.
When he looked to Lisanna, he saw her shimmering silver locks and the bright attitude he had grown to love. He had spent his childhood with this girl, his memories. They knew each other inside out.
The two looked at him expectantly, eagerly. Beseechingly, because Natsu knew that this time would come eventually, and they knew, and he just didn't-
-but he did.
Because between the two of them, there was one he couldn't live without, and one he wouldn't live without, and he knew exactly which one of the two she was.
Steeling himself, Natsu took a deep breath and stepped forward.