Chainsaw Man x Male Reader

Prologue

A mind, a conscience, a being, came to existence in the middle of the ocean. This being was a devil, more specifically, the Water Devil. It didin't have a form, rather it's body was just water which it could use to shapeshift in a way. The devil observed it's surroundings only to find water extending to the horizon in all directions. It stood there, lightly levitating over the water which started to contort in various shapes below it.

The devil had just come to life a couple of minutes ago, and there was a strong sensation on it's mind, a neccesity. An unexplainable hatred towards humans was deeply rooted in it, as all other devils. Because of this, the devil spent a very long time to kill as many of them as he could, not for any reason in particular, just for the sole urge to end them.

Countless years passed, and the devil had killed many humans. Some were even going after it, in a futile attempt to end it, just to end up devoured by it. The devil kept killing and killing, and it started to notice something peculiar. when it killed a human, sometimes other humans near it would start to completly break down and they let themselves be an easy meal. It couldn't understand the reason for this, it saw every life not as an actual life, but as an objective to strike down.

Eventually, the human emotions it saw trough the years piqued his curiosity. It couldn't comprehend how humans developed these feelings for each other, while it could only feel hatred for their species. The devil was intrigued by this but kept killing and killing and killing either way...

-In the US-

A person named (Y/N) was visiting his parents for the evening, since he was moving to another city far away for job related reasons.

"So, son have you been able to get that promotion you wanted?" asked an elderly man while he took a cup of tea. (Y/N) took his eyes off of the food and replied in a layed back manner "Well, not yet, but im sure ill get it eventually dad, i need some more time for it." The elder man raised and eyebrow at his response, and asked "And why is that if i may ask?" (Y/N) thought for a moment, thinking of an approapiate response. "I suppose i haven't gotten an opportunity yet" he replied while staring at the ceiling. The elder man was going to reply, but (Y/N) interrupted him "Hey dad, i gotta go right now, i'm gonna miss the train to the new apartment!" His dad laughed at the reaction of his son, while still laughing he said "How can you forget that?!"

(Y/N) quikly grabbed all of his belongings and left in a hurry, not before saying goobye to his parents. he walked out of the home and into the street. As he walked he thought about his life and how it had been turning up good for him. he got an apartment in a nearby city, and a sustainable job. Even though his parents were a bit low on money when he was born, they still managed to get him a good life, and he was eternally gratefull.

He finally reached the station and got in the train, sat down and enjoyed the view of the city.

After some time, (Y/N) had finally reached his new apartment. he sat down in one of the couches and fell asleep right there, while watching TV. He lived there normally for a while, away from his parents.

One day, (Y/N) woke up like any other, brushed his teeth, and sat down to watch TV. What he saw on TV that day, changed his life completly. The Gun Devil had materialized near the city where his parents lived, completly destroying everything on its path, ending the lives of over 1.2 million people in 5 minutes. it's power was devastating. (Y/N) had never encountered a devil in his life, as common as they might be, and he really wasn't worried about them, but now that he saw this power, he was completly aware of their treath.

(Y/N) registered his parents has also died, as the news rolled the enourmous amount of names which had been killed. he stayed still for some moments, before a tear fell out of his eye. the more he thought about it, the more it hurt. but it wasn't just that his parents had died that made him break down.

He was now completly alone.

...

two months had  passed since the incident with the gun devil, and (Y/N) was devastated. He was sitting in a beach, staring at the horizon. he thought about his parents, he thought about his life and his future, in complete silence. He felt like he had nothing else, he haden't realized it, but making his parents proud of him was his only objective. Now he felt like anything he did, had no meaning.

He was so inmersed in his thoughts, he almost didin't notice the figure emerging out of the water in front of him. By the time he noticed the figure, he could not breathe anymore. He fell back into the sand, there was nothing he could do. As he saw the figure looming over him he accepted his fate, thinking he didn't really have much to live for anyways. He closed his eyes expecting to die.

After having closed his eyes for a couple of seconds, (Y/N) realized he was still alive. He could now breathe again. Confused, he looked at the devil before him, why wasn't it attacking him? The devil remained before him for a while, during which (Y/N) didin't move an inch. 

The devil spoke in a muffled and alluring voice "Human, you have lost your will to live...why is that?" (Y/N) remained silent for a few seconds, thinking carefully about his answer. "A devil took the only things i had left...i don't care at this point."

The devil spoke again "Human, even though im holding back every fiber of my being to not assasinate you, im interested in you. So I'll give you a chance. What if we made a contract? I'll give you my powers for anything you desire, and you will let me see everything you experiment trough your eyes." (Y/N) got up from the sand and brushed said sand off of his clothes. "Why is it you want to see trough my eyes? And why would i want your powers?" The devil didin't show any sign of emotion and just responded "Let's just say i have an experiment i want to carry out. and as for the other question, you could attempt to kill the Gun Devil"

(Y/N) stayed silent once again looking at the devil "The Gun Devil is too powerfull, i know that. Even if i wanted to kill him, i doubt your powers could help." The Water Devil twiched sligtly when it heard this response. It looked into (Y/N) eyes, seeing his unwilliness to keep on living. 

"Then...I'll promise to find you a new reason to live"

".....What?"

The Water devil sunk into the water before speaking once again. "So the contract would be, Ill give you my powers and try to find you something to live for, in exchange, you will let me live inside you and experience your life trough your eyes. (Y/N) thought about the offer for a moment, thinking about all the possibilities. he looked straight into what he thought was the devil's eyes before saying. 

"I'll accept"

......................................................................

So, I don't know where im going with this. if this is liked enough then i suppose i will continue it.

Also, please give me any feedback you feel like i need. im trying to improve and i would love to hear your thoughts.

For anyone wondering, the water devil represents the fear of drowning and what you could find under the sea.

So for now, Bye!