Disclaimer: The characters belongs to Hiro Mashima.
Based of this prompt: " Imagine Person B sacrificing themselves to seal away their archenemy, Person A. Person A will never be able to wreak havoc upon the world again. (Until the seal weakens, that is…) The catch is they will both be trapped in another world. Together. For many years. And one or both parties are extremely susceptible to loneliness. If Person B gets tired or lets their guard down, the seal may weaken faster. What happens next?" from tumblr.
AU, Angst, death, blood. Probably OOC. You're warned
He was subdued in the church with multiples spells casted in unison. They were barely enough to contain him for a little time. Almost all of the warriors were already dead and the mages will be exhausted soon. He smiled. No one could stop him now. He just had to wait until their powers faded away…
That was the moment when he saw her for the first time. She was tiny, like she was still a child, but he could felt her power. Anyway, he was sure will still manage to defeat her and her group. Until he saw the sign painted on her chest and he understood.
"No!" he screamed but the spells were strong yet. The blonde girl started to chant and before he could do anything else the whole world disappeared.
There were just both of them in a white space. The magic also vanished and he tried to attack her but was rejected before he could touch her.
"I sealed you outside the world. This was you will never hurt someone else"
"And why are you here too?! Wait, did you… did you use your own body to seal me?!" That would explain why she was there and why he couldn't attack her before. She was the seal and he couldn't hurt her "Did your sacrifice yourself for the world?" He laughed with cruelty "Why would you do something like that? It's so stupid!"
"I don't expect someone like you to understand" She said, looking at him with something similar to pity on her face "You are Zeref, the black wizard. You can't understand all the precious things that are worth to protect"
"Everyone of you, "heroes", always say the same words. Whatever. Now we're trapped here thanks to you"
"I will guard you so you won't hurt anyone"
He clicked his tongue and tried to walk away but there was no place to go. Just the white void. He turned back after a while and looked at her. She was in the same position with her eyes closed. He sat down and started to think. There should be a way to free himself.
It wasn't fair! He had study a lot to become the strongest mage in the world. No one could stop him when he started to take control over the small cities. He was alone but he was powerful enough to defeat armies. He would have conquer the world in a few months. And then this girl appeared with the only magic that would be able to stop him. How was she capable to casts that spell anyway?
He spent days, or so it seemed, gazing at her. She only opened her eyes when he moved. They didn't need to sleep, to eat and probably they didn't need to breathe either but they kept doing it because they were used to. The time won't pass by them.
Eventually, Zeref realized there was a way to reach freedom. She was the seal so if she started to doubt, the seal will weaken. He had to become her friend so he could convince her he didn't want to destroy the world anymore. And when she believes him, he will kill her and return to the world.
That was the reason he started to speak to her. Maybe he was a little bored too. Nevertheless, she was smarter than he thought. She discovered his plan very fast and he was impressed. He asked her name and she refused to tell him. He asked again. And again.
"Why are you so interested in my name?" She finally said.
"Because you know mine and I have to recognize you're good enough to bothering knowing yours" It wasn't a lie altogether "And we don't have anything else to do"
She looked at him for a long, long time. It could have been days.
"My name is Mavis" She answered and then shut her eyes again.
Zeref didn't say anything else. He just sat there and thought again. How much time would have passed? It really didn't matter because he would be the same when he return to his world. But he was curious. It would be summer outside? Maybe winter? Perhaps it was snowing? Why he was interested in something so stupid as seasons? Why did he bother? Well, his little brother liked snow when they were kids and he was still alive. How many years ago was that?
"Do you know how much time we had been here?"
Again, she took her time to answer.
"I have no idea"
"Oh"
The silence fell over them again and that white space made him think of all the things living outside and made him curious again.
"What are those things you said were worth to protect?"
"Why are you asking that?"
"Probably because I'm bored"
She looked at him and then closed her eyes and answered. It was a long answer. She talked about all the things she loved. Flowers, trees, rivers, animals, autumn breeze and spring rain. The laughs of the kids, the little smile of the elders, the strength of the youth. The happiness of having friends, the excitement of discovers something new, the hope that never dies. And many, many more things.
And he listened because he didn't have anything else to do. When she finished he just said
"I like your hair"
"What?"
"It has nice curls"
He wasn't sure why he told her that. Probably it was that day when things started to change between them. It was slow, of course, but they had all the eternity. At some moment, many years later, he asked if he could touch her hair and she said yes. After that, he sat beside her and she sat down too. And they talked about nothing and everything. He discovered he could fall asleep if he tried. She found out that since she created that space she could change it too. And she brought all the things she loved to fill the void. He learnt to love them too. And, at some point, he learnt to her too.
Some day she fell asleep and when he looked at her, he remembered that he wanted to kill her once. He laughed at himself. He was so stupid then.
One day he dared to kiss her and she smiled and kissed him back. They were happy exactly the way they were. And years passed by. Centuries. Millenia. And they were trapped together in their own space forever. Or at least they thought it was forever.
They were sitting under a tree when a crack appeared on the sky. She didn't scream but he felt her tension. And something wet on his hand resting on her waist. He looked down and found a stain of blood growing fast on her clothes.
"What is happening?!"
"Someone… is breaking the seal"
"What!? NO! I have to stop them, I have to… " He looked at her eyes and saw the truth written on the green pupils "I can't lose you too!"
He felt something dragging him but he didn't want to let her go. She kissed him a last time and said.
"Please don't destroy the world" That was the final thing he heard from her but he could read her lips before everything disappear.
"I love you"
He returned to the world at the same spot he left it. The old church had disappeared and the only wall remaining was the one where the seal was placed. He once thought he would return proud and ready to destroy everything. In contrast he was a mess, kneeled on the ground, crying and with his hands soaked in blood. Her blood.
"Master Zeref, we had succeeded! You came back to us!" He looked up to the man who spoke "Master Zeref?"
"What have you done!?" He didn't think. He just release a wave of his magic and everyone became a pile of ashes.
The he stared at the wall. To the seal broken in half. It was slowly vanishing. He tried to fix it with the blood on his hands. Maybe her blood can save her. Maybe she could come back too…
Sorry... I'm sorry. But I had to.
Cya!