Disclaimer: I do not own Fairy Tail or any of its characters.
"Ah, so these are the ones that you think will send me into oblivion?" Cain asked harshly. He stared at Sonja. Hoping that maybe she would wake up and find a better solution, fighting was in his blood but he never liked hurting old friends. Sometimes he thought about how they were as children, best friends. She was purely demonic until puberty that is when she learned of her mother, that she was half angel. After that Sonja changed instead of hunting and causing enough chaos that even her father had scolded them, she wanted to be like her mother, pure and innocent.
Sonja didn't say anything as she positioned herself behind the boys to provide backup. She would protect the boys as they moved in for the kill. She hated Cain through and through, no matter the past. It didn't matter that they were once friends, he was all evil down to his core. Any one that could cause the pain and suffering of good people and mages deserved to die. She saw the pain in the dragon slayer's eyes every time they heard Cain's name. She was sure he had caused them unspeakable pain. In front of her were good men, strong and loyal to their beliefs. Her new family replaced her old one and she would do anything to protect them.
Cain walked up and gazed at Sting's body, "It's a shame that the demons only fucked Sonja," he said. Sting felt violated at Cain's gaze he shrank back at the thought of Cain touching him. Cain just laughed at Sting's reaction to him. He truly was done fighting, this war was lost, everywhere around them demons lay dead or dying. Sonja had done everything to win this battle as the Goddess of War there was no beating her. He was just angry, angry at the world for his fate and everyone's here they have all been destined to die for Sonja genocide of her own race that she once claimed proudly. He was nervous about the boys striking him, they had to combined power that could kill him, he figured he should mentally beat them down. If he could distract them enough he might actually be able to gain the upper hand. He was sure that the boys had everything done to them except that unforgivable act of torture. He wasn't even sure if his words had any effect on the boys, they had seen horrors that most humans can't live through so his mockery might mean nothing.
Cain giggled, "I bet you watched as the demon took the only thing that was never dared taken from the princess, you," he eyed both Sting and Rogue, "are cowards." For once he actually meant what he said. Friends or not he wouldn't have allowed anyone to hurt someone he cared about, they were cowards for allowing that demon to touch her when she had risked her own health protecting them.
Rogue looked down as he was assaulted by the guilt that he had been hiding. He blamed himself for not protecting Sonja that day or any other day. He would never forget seeing Sonja's tears, her eyes weren't just watering from pain that day, she was crying for the loss she felt. He often awoke from nightmares because that sound of the demon haunted him. Since the Grand Magic Games Rogue was constantly on guard to make sure that his inner darkness never rose up, he was confident in his physical power but he often doubted his ability to stay awake from the darkness inside him. The shadow demons brought out something within he wished to bury, even worse they made him hurt his best friend. What scared him most was that it was easy to just let go and let his darker half deal with it, the physical and emotional pain stopped. Everything went dark he couldn't feel a thing.
Sting looked at Sonja. She looked astonished that Cain knew what happened to her. Sting felt guilty for not coming to her aid and letting Sonja take the fall. But he knew Sonja didn't blame him for it, she hated the demon that did it. "You don't know anything!" he shouted as he roared at him. Cain didn't suspect that Sting would be clear headed enough to fire at him and didn't have a chance to move out of the way. He was shocked to see that the dragon slayer attacks dealt the most damage to his dragon bone armor. Sting ran up and started hand-to-hand combat against Cain. Sting's Light Dragon Slayer magic did the most damage. He was the human embodiment of light while Cain was dark, without his armor Cain wouldn't last very long in a magical battle between him and Sting.
While Cain was distracted Sonja ran over and grabbed Rogue, "Look at me," she moved his head so he looked in her eyes, "what happened to me wasn't your fault. I forced you and Sting to stay away from me. You wanna repay me? Kill him, repay him for the torture I received," with that she turn to face Cain. Sonja didn't bother to wait to see if her words had any effect of Rogue if he wanted to fight, to get any vengeance over their past six months then, he had to fight that guilt away. Rogue stared as Sonja ran back into battle, he would always feel some guilt over what happened but he knew that he needed to repay her and if defeated Cain would solve even a tiny bit of that he would need to redo it. Rogue renewed his determination.
"Cain!" Sonja shouted. Once Cain looked at her she charged, she could believe that he knew about what happened to her and did nothing. She prayed and hoped that the sick and twisted demon acted on his own but she realized that everything that happened to her was ordered by her brother and Cain. She smiled and hoped that dumbass demon bragged about what he did and her father would hear about this, no one had a sicker mind than her father. His torture would be far worse than anything she dealt with, he hoped that the demon would feel the pain that she and her comrades had felt. Her father would make sure that the demon would pay for any pain she felt ten-fold, and she was her father's favorite, so Thorn would pay as well.
Cain fell under the force of Sonja's fists, she covered her fist with Hell's Fire. Even the strength of his armor could not withstand her punches. She was done playing it safe while fighting, she knew that this poison was gonna kill her and she would only speed it up by increasing her heart rate but she would not allow Cain to insult her comrades, or mock the brutal torture she withstood at the hand of her own kind. The adrenaline flowing throw her veins only strengthened as she felt the power of the battle going on around her. She was getting stronger faster than she was getting weaker. The strength of Fairy Tail was feeding her. She smiled at his weakness, he was nothing without his armor. His shield was falling apart under her brutal assault.
Sting noticed that Sonja was buying them time he stuck his arm out and started to build a ball of light and Rouge followed suit. This brought Sting back to a time before Sonja, when everything was simple. The Twin Dragon Slayers would kill anyone that their guild sent them after, now Sting regretted that he could follow them so blindly. He often thought about if they deserved to die or if they just pissed off the person willing to pay for them to get killed. He thought of the Grand Magic Games, he had made so many mistakes during that time, but after fighting with Fairy Tail and Natsu he started questioning everything he did for the guild, Natsu's courage for his Nakama was legendary. He wanted the same thing.
Rogue started to build his magic in a ball so they could hit Cain with the unison raid. They had one chance to get this right, he needed to kill Cain. Rogue was rarely the type to have blood lust but after the past six month he wanted his hands stained with this demon's blood. He needed this for himself, for Sting and for Sonja. The trio had suffered so much by Cain's hands now it was time for him to suffer.
Sting and Rogue looked away as the power grew, Sting's magic burned Rogue's eyes. At the last second Sting and Rogue both shouted, "Sonja! Move!"
Sonja looked up and smiled, her sweet boys had taken the time to deliver the killing blow she held him down until the last possible second, she seen the horror in Cain's eyes as the magic blast was coming at him. She moved behind Cain and put him in a full nelson, she forced him watch as the ball came closer. She wanted him to watch his death before it actually hit him. Sonja knew he couldn't jump out of the way he would have to take a direct hit. She knew that amount of magical energy was extremely lethal if she didn't move quick enough than she would lay dead along with Cain. As the ball moved closer Sonja went blind from the light and the overwhelming magical energy made hearing impossible, she shut off her human senses and left only her pure animal instincts. At the last second something within her told her to move and she jumped off Cain.
Once the dust started to clear Rogue and Sting started to look for Sonja. Panic set in when they couldn't see her, "Sonja!" Sting yelled.
They heard a slight cough and a chuckle, at first they thought that it was Cain until they seen Sonja on all fours and she lifted her head and smiled at them, "Wow boys you guys sure can pack a punch."
The boys ran over to Sonja, Sting was shocked when he seen that she was coughing up blood, "Oh god, did we hit you?" Rogue said with worry.
"No boys, I got out of the way in time," she told them. She looked over at Cain, he wasn't dead but he was knocked out, she took a blade out of her armor. "Boys help me up please?" she asked.
The boys lifted her up and watched as she stumbled towards Cain. She reached him and sank to her knees, "Look away, you don't need to see this," she raised the blade over his heart. She looked to his face one last time, he wore a smile and looked back at her with sad eyes, he knew what was coming and excepted his fate. Sonja tore her eyes away from his face and concentrated on his chest she inhaled deeply and with her exhale plunged the dagger deep into his heart. Cain turned to dust and washed away with the wind. She started coughing up more blood, she knew she didn't have much time left but was proud that she was able to take away Cain's threat to Fairy Tail. She returned to her human form and sank to her knees.
Sting rushed over to help Sonja up. He could see her strength fading. She was leaning heavily on him, "I thought you said only a human could kill a demon? Why didn't you allow us to finish him?" he asked.
"My father will have something even more special planned for him once he figures out his crimes. He will pay for happened to us, I promise." She replied with a smirk. Sting was going ask what would happen but the sadistic look in her eyes told him he didn't truly want to know. Sonja started to waver and fall, Sting caught her before she was able to actually lose her balance, "What happened? You aren't yourself." He had personally seen Sonja handle more damage while in the dungeon and now she looked like she was dying.
Sonja sighed, she hoped that no one would notice her weakened state but it was obvious that she was dying, "I sucked all of the water from the river Styx out of Natsu's blood stream, it is poisoning me," Sting and Rogue looked at her. Her stomach was burning as well as her veins, she could feel the water running throughout her body. She guessed she had about ten minutes before the poison took her life.
"But you are immortal, heal it!" Sting said desperately. He was overjoyed at their newest victory but the thought of celebrating without Sonja sickened him. She deserved to go home and celebrate with her family, the people that loved her. She had been surrounded by hate and despair for six months she needed this battle to be over more than anyone.
"I gave up my immortality when Natsu didn't wake up after I took the water out of him," she looked away. She knew that the boys wouldn't take her dying very well. She felt guilty over leaving them.
"What does that mean?" Sting said. He hoped that she wouldn't confirm his suspicions.
Rogue placed a hand on Sting's shoulder, "She is dying and no one can save her," he said with tears in his eyes.
"I am sorry boys. I couldn't let my brother kill my mate," she told them.
"Does Natsu know what you did?" Rogue asked.
Sonja shook her head, "Please don't tell him. He wouldn't want to live knowing it was at the cost of someone else's life," she told them. The boys looked at each other in silent agreement, Natsu would understand that his life was at the cost of hers, they loved her too much to let her slip away into memory.
"Take me to Natsu, I want to finish Thorn before I am done," she asked them. She couldn't seem to say out loud that she would be dying in this battle. She looked around and seen her friends fighting, she tried to think about how their lives would change without her. She didn't know them personally for very long but she knew that they were all important to her, if any of them died in this battle she would have been devastated. She protected Fairy Tail and all of Earth-land from the demonic underworld for so long she wondered if the demons might take control after she had gone but hearing Lucy's and Gray's yells as they were fighting swept the thought from her mind. Her friends and the next Fairy Tail generation wouldn't allow the demons or the dark side to rise, they would stand there side by side and never wavering as the demons fell before them. She smiled at the thought of the next generation, she wondered how Fairy Tail would be in ten or twenty years, but she knew that she could trust them with the future.