Natsu had imagined a life without Lucy before this instance. These thoughts would come to him in his worst nightmares, or at times when he was weak and vulnerable. Before he had met her, he had been lonely, believe it or not. Sure he had his other guildmates, but he felt disconnected from them. After he lost Lisanna, he had distanced himself from the others, afraid that he would lose anyone that he deeply cared about.
And then came Lucy. He was attracted to the blonde mage right away, but he pretended to have no interest in her whatsoever. He had tried ignoring her, acting cold towards her, calling her a weirdo, which may or may not have been true, but he couldn't stay away. He eventually formed a team with her and they became best friends. Lucy helped him open back up to the other guildmates and she became the glue that held their team together. Throughout their adventures and the many years they spent together he had discovered something. Lucy had become his ultimate weakness.
The thought of losing her terrified him. She was his best friend, his partner, his Lucy. Natsu had realized that he couldn't live without her. So with his newfound fear came nightmares. He had horrid dreams of losing her, watching the color drain from her face, desperately holding onto her as her life slipped away. These nightmares worsened after the Future Lucy died right in front of his very eyes. After Igneel's death, they got worse. He was scared of losing the ones he loved, so he left to train for a year. He wanted to become stronger, that way he could protect her.
And now at this very moment he was holding her cold, lifeless body. The war was still happening in the distance but Natsu's world had stopped. When he first stumbled upon her body he was too shocked to even move. He was paralyzed. His heart sank into his stomach and then he slowly walked toward Lucy's body. At first he tried to deny the inevitable. Maybe she was still alive?
"Lucy?" Natsu called out. There was no response. "Lucy!" This time he called out louder. At this point he reached where Lucy was situated. The very sight of her made his stomach churn. She was in her Aquarius star dress, except her top had been removed to expose her bare chest, but that was the least of his worries. She was bleeding from her head, and there wasn't a patch of skin on her body without a cut or a bruise. All the color had drained from her face, and Natsu couldn't find a pulse during his panic. What had this Dimaria woman done to Lucy?
Natsu wrapped one of his arms around her waist, and placed the other behind her neck. He held her face close to his. "Lucy! Why aren't you moving?!" He continued to cry out for her, longing to hear her sweet voice just once more. He placed his forehead onto hers and ran his fingers through her soft, golden hair for what might be the last time. He continued to cry, and cry, and cry…
This was all his fault. He wasn't strong enough. He had promised her he would protect her but he couldn't even keep her safe. He promised her they'd make it through the war, that victory would be theirs. Did it even matter if he made through the war now? Lucy was his everything. Who would he go on missions with now? Whose apartment would he break into? Whose bed would he sleep in? Who would he spend all his time with? Who would laugh at his lame jokes? Who would hug him and be there for him when he needs it the most? His best friend was gone because he wasn't strong enough to save her. But he wasn't the only person to blame. The war was Zeref's doing. Nobody in Fairy Tail asked for any of this. Zeref dragged them all into this war. Zeref was the reason why Lucy was lifeless on the ground, the reason why Natsu just lost the most precious person in his life. Zeref was going to pay. Natsu was overcome by his anger, and he felt himself lose consciousness. What awoke was not Natsu, but a fearsome monster willing to destroy anything in its path.