Natsu's Sacrifice

Team Tenrou stared at Acnologia, the black dragon with blue patterns, who was in front of them. It couldn't get any worse than what they were experiencing, they were all exhausted from their previous attacks and knew that they couldn't withstand another attack.
'It's all over if I don't do anything now.' Natsu, the pink-haired Fire Dragon Slayer thought to himself, knowing that all of them weren't going to escape alive. The only option was to dwindle the casualty count.
The Fire Dragon Slayer stood up from the group and walked to the black dragon with fear the last thought in his mind. The rest of Team Tenrou was confused but only one spoke out. 
"Natsu, what do you think you're doing." It came from the red head Erza Scarlet. Natsu stopped for a second, he took off his scarf and tossed it to Erza. 
"Keep it safe for me." Natsu told her. 
"Don't do anything stupid Salamander." This came from Gajeel, the Iron Dragon Slayer. Natsu just looked back at all of them with his signature grin. "Everything I do is stupid." 
Natsu took a huge run with incredible speed and jumped into the sky towards the Black Dragon of the Apocalypse. The people below looked at the dragon slayer wondering what he would do when a shout came from him. 
"Dragon Slayer Secret Art: Crimson Lotus Final Rebellion!" 
Flashback 
"Natsu, I'm going to teach you a spell that can rival the strongest on this earth." Natsu looked up to his foster father Igneel. "Really it's that strong, teach it to me right now dad." 
"Soon, but I need to teach you the barter." 
"I know, I know my magic energy to cast the spell." 
"No, this spell has a higher cost, to truly cast this spell it is in exchange for your life!" 
End flashback 
Natsu's attack hit straight on target, right at Acnologia's heart. From there a huge blast of fire erupted from the point of contact. The oceans created waves and the wind became more powerful as the blast continued, and then it stopped revealing a black dragon with a hole straight through the chest where the heart used to be. The dragon fell out of the sky while trying to release it's final breath. 
The Tenrou Team looked up amazed at what Natsu was able to do by himself when they didn't leave a scratch together. That was where the amazement ended, they didn't see any sign of the Dragon Slayer's body descend and that was when the team realized the high price of the magnificent spell. 
"I don't understand. Where did he go?" A man with two metallic wings questioned in confusion. He was Warren Worthington III, also known as Archangel. 
Makarov and Gildarts' body locked up without a single movement, eyes locked in shock. Mirajane and Lisanna ran to their brother and buried their faces in Elfman's chest, while feeling his tears roll down onto their heads. Lucy and Wendy were trembling at the sight, crying uncontrollably. Cana, Freed, Bickslow and Evergreen stared at the sight, not believing something like that had happened. Laxus, Gray and Gajeel yelled at the sky full of rage while tears streamed down their cheeks. 
Gray: "YOU IDIOT, THE GUILD ISN'T COMPLETE WITHOUT THEIR FIRE DRAGON!" 
Gajeel: "YOU DUMB ASS FIRE DRAGON. THERE WAS ROOM FOR TWO DRAGONS IN THE SKY!" 
Laxus: "WE WERE GOING TO MAKE THE GUILD STRONGER NATSU!" 
Juvia went to Gray, while Levy went to Gajeel trying to comfort them but their tears were breaking the illusion. Lily and Carla were stunned as the sacrifice. Happy stared at what was once the place where his best friend stood and fell over not willing to stand up and face what had happened. 
Erza stared long and hard at her friends and then at the dragon's corpse until she couldn't take anything anymore. She ran away into Tenrou Island until she lost strength and collapsed. She cried for hours into Natsu's scarf uttering his name, a few hours later she felt someone touching her shoulder. She lifted her head to see Happy, she scooped him up and they both continued to cry in the embrace. 
Erza thought of the times when the pink haired hero had fought for her safety. She constantly remembered in the Tower of Heaven when he fought with Jellal and ascended into Dragon Force to keep her safe. 'Who was going to be able to do that now.' 
Happy was deep in thought when Erza held him while they cried. He had only felt this hurt once in his life, when Lisanna disappeared and was thought to have died. He couldn't have lost his dad so soon after his mom had returned, not after he had his full family back together after two years. The thought made Happy cry into Erza as she held him. 
It was late and the pair had cried themselves to sleep until a man shook Erza waking her and Happy up. When they stared at the man they recognized him instantly as Gildarts and he spoke. "I know I was not his father or his adopted one, and he was definitely not my flesh and blood. But it damn well feels like I lost a son today." Tears came down his stoic face. Erza knew how close Natsu and Gildarts were. 
"We're leaving the island and returning to the guild now." The words came thick and heavy from Gildarts's mouth. 
"No, no, no, no, I can't leave him. What if he's still alive and we need to sa-" As Erza spoke Gildarts lifted her off the ground. 
"There's nothing left to save! And as much as I hate it, we need to hold a funeral." Finally letting his face show how sad he was at the events that had happened today. 
As Erza was held by Gildarts she could only cry while clutching onto Happy. When they got on the boat and set sail she looked at Natsu's scarf and said her final goodbye, 'Farewell, the dragon that kept me safe. My dragon.'