I added a paragraph as a hint which is linked to a revelation in S4.
Chapter 16: Natsu's will
Natsu, Lucy, Gray, Wendy and Charles watched from in a distance as the light of the Etherion hit the target. Instead of having the tower destroyed, the form of the tower changed after the attack. The metal surface had disappeared and in place of it, was a crystal-like structure with just one main trunk of Lacrima shooting up to the sky and a few branch-like crystals protruding unevenly from it.
The group was actually relieved especially Natsu. He was worried about his brother who was likely to be on the Tower the moment the Etherion was fired on it. Wendy could very well observe his change of expression.
She felt very uneasy. How was he able to stand here? She knew he would not answer her honestly if she asked him directly. The only way to know was to ask Brain and Cobra who had left abruptly after she fell unconscious and even Jellal if that was possible. What exactly Brain did to Natsu? Wendy pulled Natsu to one side to inform him of her decision. She did not intend to let him know her plan.
"Natsu-san, I intend to search for Jellal. Meanwhile, don't do anything reckless and strain your body if you are not feeling well." Wendy was very worried when she saw Natsu in pain earlier in the cave when he was found and she was feeling very anxious trying to help him feel better.
"Don't worry, Wendy. I had gotten enough rest earlier and I'm feeling a lot better. See!" Natsu reassured Wendy. He was well aware that he would be stopped from looking for his younger brother if she known of his condition.
*Flashback*
Despite feeling energetic announcing to Lucy and Gray about his recovery, he did not feel well. In fact his vision got blurry from time to time from the effect of two types of poisons running through his body. "I need to hang in there, just for a while. Just for a while." Natsu slapped himself on his face to stay awake.
*End Flashback*
"Alright, I shall bid farewell to everyone here. Good luck, Natsu-san." With that, Wendy took off with Charles in search of Brain and Cobra.
Not saying any words after Wendy had left, Natsu ran off aiming for the top of the tower to go after his younger brother. Gray and Lucy chased after him when they saw him running off. Natsu reminded himself that he would just focus on climbing to the top and nothing else.
"Natsu, wait!" Gray yelled at him to slow down. Lucy was trying her best to keep up with the boys in front. The group was climbing from the surface. All the sudden, Natsu heard a voice ringing in his mind.
"I'll lend you my power, Natsu." Natsu shivered when he thought he saw a sadistic smile in his mind. He felt light-headed all the sudden and he lost his balance.
He was stunned when he found himself falling from great height.
"AHH!" He yelped.
"Natsu!" Gray and Lucy cried in unison when they saw him falling. Gray realized he would not be able to reach his hand on time. His eyes widened in fear when he saw his friend falling and disappearing from his sight.
"NATSU!"
"Here I come!" A voice was heard from afar. A figure sped up and caught Natsu on time. To Natsu's surprise, it was Happy.
"Happy!" Natsu turned behind to greet his saviour.
"Long time no see, Natsu." Happy greeted Natsu and flew him around.
"This is so cool! You are my hero." Natsu commended the blue Exceed.
Gray and Lucy heaved a sigh of relief. "The two brothers are going to scare me to death sooner or later." Gray commented while Lucy smiled apologetically.
"It had been a long time since Natsu and I become one with the wind. It feels great, isn't it?" Happy asked Natsu who agreed with him. "Yeah, it had been a long time. This feeling is just so wonderful!" Natsu looked ahead.
They landed somewhere where Happy could talk. "Tsuna said he is going up to face Jellal alone and suggested that I find you guys to see what you guys are doing. I didn't expect to see Natsu here. Natsu?" Happy glanced at Natsu who was staring into space.
Natsu was full of worry. What was his brother thinking when he kept Gray away from him?
"Damn! He didn't know Jellal up there is a fake." Natsu recalled the dream where Tsuna suffered an utter defeat against "Jellal".
On the other hand, the committee did not expect things to turn out this way. The tower was not destroyed but had "evolved" by absorbing the power of Etherion. That was when they realized they had been tricked. Yajima approached Ultear to demand for an explanation when he noticed that the building was collapsing and she was the culprit.
"Time of Ark!" Ultear turned to Yajima's direction. "They are going to be there. The rest are up to you. Proceed according to plan, because you can do it, Jellal." "Jellal" over at the top of the tower had heard her via telepathy.
"Understood. I, Jellal will accomplish this mission." He sat with his hand on his chin. He was currently facing a woman with a hair of scarlet glaring at him in fury. "Come at me, Elsa!" He smiled evily.
The Council had fallen. Despite this, the Sage of the Magic Council. Org did not lose his composure.
"Send reinforcement to take the tower down and take in those involved in custody."
Natsu and the group noticed the arrival of the reinforcement from The Magic Council. It seemed that they would capture anyone involved in this operation in sight. He did not wish to be stopped here. He needed to get to Tsuna fast. Gray saw his worried expression and understood his fear. He had thought Tsuna had matured but it seemed that he was wrong. That boy was still as reckless as ever. Tsuna was the younger brother of Natsu after all. They were one of a kind.
"Natsu, go ahead." Gray patted him in the shoulder. "We will hold them back here. Look for Tsuna and bring him back. I'll be letting you down should anything bad happened to him."
Natsu blinked at Gray in surprise. He did not expect Gray to offer to help him. He put his hand over Gray's as he responded trying to reassure Gray that Tsuna would be alright despite his worry. He did not want them to get them involved with his problem.
"Don't worry about him. He is more powerful than anyone of us here." Natsu grinned at Gray. He was really grateful to have his friends around him supporting him. If he had a choice, he would not leave Fairy Tail. He turned over to Lucy who was behind Gray and approached her.
"Lucy…" He gave her a small peck on her cheek causing the celestial mage to blush madly. Gray averted his eyes pulling the Exceed by his wings and left the couple alone while they keep a watch for incoming enemies.
"What is this?!" Lucy replied in panic. Natsu scratched his cheek blushing. Since when he had the gut to do that? He gave her an assuring smile coming from his heart.
"Perhaps, this is my last chance to do so. I will account for my feeling towards you. I like you. I really do." He pulled her into a hug. "Lucy, after today, please look for your happiness. I'll give you my blessing no matter where I'm." Natsu moved to her ears and whispered something which made Lucy shuddered in bewilderment. "I'm grateful for Granny to give me this chance to be with you even if it is for a short time." Natsu pushed her away when he finished, taking off before Lucy could react.
"What is this?" Lucy felt empty. "Natsu, you will come back after this right?"
Gray who was watching out for the rune knights from the Magic Council when Happy was taken by surprise but he managed to dodge their attack on time. They had been found.
"Looks like Natsu had gone ahead." He thought when he saw Natsu's running figure far ahead and Lucy was watching behind.
"Lucy, stop staring into space. Come and lend us your hand!" He ordered as group of knights had already surrounded him. Gray took his position and prepared to engage them.
Natsu was in tears after he ran off. He knew about the Granny who granted Lucy her wish for Natsu to live on. He did not belong to this world. Besides, the poison in his body was incurable. All he could do was to request Brain to slow down the effect of the poison granting him some time for him to do something.
"There is something I have to do and only I can do it. I will change their fates. Wait for me!"