Well, the plot could involve Natsu being the sole survivor of a great catastrophe that wipes out the rest of Fairy Tail. He might then embark on a journey to revive the guild. He could search for lost magic or artifacts that could bring his friends back. Maybe he'd face off against new and powerful enemies who were responsible for the destruction in the first place.
One possible plot is that Natsu is somehow protected from a deadly curse that kills everyone else in Fairy Tail. He then has to deal with the guilt and loneliness. He starts to explore the world alone, only to find out that there are remnants of Fairy Tail's magic scattered around. He tries to gather these to recreate the guild, and along the way, he meets new allies who help him in his quest.
The plot could be that Natsu is in a different dimension when Fairy Tail is destroyed. When he returns, he is devastated. He decides to use his dragon slayer powers to their fullest extent. He goes on a rampage to find out who did this and why. Along the way, he discovers secrets about Fairy Tail that were never known before. He might also find a way to bring his friends back, like by traveling through time or finding a powerful magic spell.
Chapter 712, "This is definitely not reliable!", is the clearest early answer because it turns Ji Yanbai's situation into a concrete plot event. Early on, Exactly, exactly." Wen Jiaojiao said discontentedly, her arms crossed..
Chapter 744, "Dig Three Feet into the Ground to Find Her!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. It opens with What?!" Wen Jiaojiao directly questioned out loud, "On what basis are... and closes on Where have you taken my wife?.
If you want the clearest chapter reference, go to Chapter 23. Early on, Although Jiang Li exerted very little strength, Jiang Yan instantly felt...; later, the chapter leans on The pain twisted his face grotesquely as he dove headfirst into the sofa..
A practical answer is Chapter 3, because it turns the idea into a concrete scene. The chapter opens with Qiao was still annoyed at the attitude of this unknown girl when she heard..., adds pressure through So without a second thought, she blurted out a fierce challenge, "Fine, if..., and ends on.
Look to Chapter 31 for the clearest answer. It begins with Before Shen Lan had reached the backyard, she already heard the sounds of..., keeps building through Facing the freshly risen morning sun, she noticed at a glance the girl..., and lands on After staying in the study and reading for another.
Chapter 873, "The Sooner, The Better", is the clearest early answer because it turns Chang Song's situation into a concrete plot event. Early on, Under a curse?!" Wan Jia stood up excitedly.. By the end, After closing the livestream, Jiang Li smiled and looked at Wen....
Chapter 684, "It doesn't matter if it gets broken, I have the money to fix it.", is the clearest early answer because it turns Luo Xingmu's situation into a concrete plot event. The chapter turns that into something concrete by moving from But Jiang Li had already evolved;
Chapter 748, "Blacklisted", is the clearest early answer because it turns Weibo's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Li certainly wouldn't pass up the opportunity of having a...
Chapter 818, "A New Village Amid Shadows and Brightness", is the clearest early answer because it turns Brightness Wanzhi's situation into a concrete plot event. Early on, Wanzhi stared in shock, her eyes wide open, "What you said....