This is my idea of what Natsu would've done at Lisanna's Grave. While reading open a different tab and go to YouTube type in Fairy Tail soundtrack and listen to number 29 "past story". It sets a mood.

As the pink haired mage stared down at his cold friend's grave all he could see was her face and all he could hear, apart from the sky that was crying, was her voice. "You see Lisanna, Even the sky's gonna miss you." Natsu fell to his knees and kept his face down, and he could feel warm tears fall down his face. "Why did you leave?" He said punching the cold wet ground. "Are you just gonna leave me, and your only son, Happy?" He struggled to say between his anger and his tears. He remembered her face those blue eyes that gaze at you and make you feel the warmth of optimism, even before your own death. Natsu's anger began to evaporate slowly just like Lisanna's soul." You know Lisanna… Mira told me something." He said with a smile, he noticed that every time he said her name his heart would skip a beat. "She said you had a crush on me, I had no clue you felt the same way." Natsu couldn't stop his tears they were uncontrollable and inevitable." I was gonna tell you something before you went on that mission with Mira and elf man, but I didn't know what to say." He said sobbing." But I guess it's too late now, but if you can hear me." "Lisanna I love you." Natsu, with all his energy, brought himself to his feet and gave his back to the grave. He raised his head and with one of those dragon slayer smiles he pointed his finger to the sky like his cold friend once did, and with tears in his eyes he said" Lisanna! I'm heading off!'' he walked away never to see her smile again.

Okay so this has a lot of "you need to watch the show." stuff in it like the whole I'm heading of thing and the happy thing. But other than that did you like it.