I tried to give him the body of a fallen soldier. There were plenty of corpses available. At least, as an adult, even if he would be a bit weaker and it would take a while for him to adjust, he would stand a fighting chance. However, his soul rejected all of them.
I was tempted to try to find a compatible living soldier. With deaths so common, one person's death would be easy to fake. But he might also become suspicious if a person whose body he could inherit just happened to die as soon as he needed a vessel. In the end, he chose to be completely reborn.
He was born as a child in the midst of war.
His father was a soldier. His mother was a nurse. They lived on the front lines of the war. Day after day, the father would go into battle and fight for his life. Day after day, his mother tended to the wounded, attending to their needs as much as she could. The boy watched all of this as he grew up. He befriended many soldiers and trainees. He watched as they left to fight and never returned.
He was too kind. That was what ruined him.
If a kind person is in the midst of war, watching as his friends died to demonic enemies, what would he want most?
He would want the war to end.
What would be the best way to end the war?
To defeat the enemy as soon as possible.
What was the best way to defeat enemies?
To get stronger, kill as many demons as possible, then take the head of the demon king.
He was kind, so he killed.
He became very good at killing.
...
"Fuck!" A man dressed in grey robes yelped in surprise upon stumbling upon the scene. There was a figure drenched in black blood squatting in front of some demon corpses. It appeared to be a boy. And he didn't have any clothes on.
The boy turned to face the man. The man trembled and backed away slightly.
"Hey, why'd you sto- Oh fuck!" A young woman in similar grey robes came up behind the man and saw the boy run off.
"What was that?" she asked the man.
He shook his head. "I don't know. But he looked human, and..." He gestured at the corpses.
"Oh my."
"Wow."
A tall knight dressed in plate mail and a young man with dark green robes joined the first two.
"Did you see who did it?" the knight asked.
"It looked like some kid or something. Around seven or eight years old," the first man responded, sounding disgruntled. "He was injured but he ran off before I could offer to heal him."
"Stop with the bullshit," the girl in robes interrupted. "You looked ready to attack him."
"Sis... You shouldn't swear so much."
"Don't you fucking tell me what to do."
After admonishing his sister, the young man turned toward the healer who looked away guiltily.
"You shouldn't swear so much either."
"Fuck, don't drag me into this, I didn't do anything."
"Now, now, calm down," the knight spoke firmly. "It sounds like this boy you saw has talent. We need someone like him. A healer, a knight, and two mages don't form a balanced group, don't you agree?"
The party expressed agreement, but also held some doubts.
"He's just a kid," the healer grumbled.
The knight nodded. "That is true. But if he's this skilled at such a young age, he must have a strong teacher."
"And we can find this teacher and get him to join us, we'll be set!"
So the party of four set off to follow the tracks of the boy and got miserably lost for the rest of the day.
...
The boy went to a nearby stream to wash the blood off himself. He jumped in, scrubbing furiously to remove the black blood. He had a small cut along his arm which reopened while he cleaned himself.
When he was certain there was no blood left on him, he got off the stream. He put on the clothes he had hidden in the hollow of a tree. Now he looked nothing more than a boy who spent his afternoon playing in the river.
He hid the knife he had stolen and traveled through the forest carefully, leaving almost no tracks. A skilled tracker would be able to find him, but he had learned how to avoid leaving obvious traces.
He seemed a bit disappointed, despite all the demons he killed today.
...
"We couldn't find him..." The female mage sat down on the floor as soon as the group returned to their camp.
"Maybe we can ask the base tomorrow?" Her brother suggested. He seemed a bit embarrassed that his tracking skills were not up to par.
"Ask what? 'Hey, do you know a naked boy who can kill twelve demons at once?' They'd think we're crazy." She snapped back.
"He was naked??"
"Did we not mention that?"
"No you didn't."
"Damnit. Can you two shut the fuck up?"
The two looked at each other and giggled.
"It amazes me every time, but I've never seen a more vulgar priest than you." The knight smiled.
"You shut up as well," he grumbled.
The knight turned to the siblings. "Don't mind him, he's just disappointed."
"Yup."
"We know."
"Hmph."
"Let's ask around the base tomorrow evening. We just have to ask if they know a boy. There shouldn't be many this close to the fighting. They have so many people, surely someone would know something?"
The brother gave an 'I told you so' glance to his sister, and she frowned.
"Why in the evening?"
"Doesn't he go out fighting demons by day? That's our job, too, did you forget?" The knight asked teasingly.
"Aaarrrggghh I want a break already."
"We'll get a break when we kill the demon king," the priest broke in with a rare, serious tone.
"He's right," the knight said gently. "We have to kill the king for all of this to end."
...
"The people who saw me, did you send them?" the boy asked me in his dream.
- Yes. They would have been the hero's party.
"One knight would have a hard time protecting three people."
It was a party optimized for either a single strong enemy or many weak ones. If they encountered any other enemy formation, they could be easily wiped out. Not to mention that some demons could resist magic.
- They lost their swordsmaster recently. That's why they aren't fighting in the front right now.
"A sword, huh. I wonder what that would feel like." The boy swung him arm around experimentally as if he was wielding one.
His battle experience and Weapons Mastery let him see the differences between a long sword and the dagger he was currently using.
- You're too young.
"I know that. My dad? He's pretty strong."
- He will die.
"... Could anyone el-"
He broke off and frowned.
"Is there anyone else who could fill in the position and still... survive?"
- No.
"..."
He seemed conflicted. His father was undoubtedly one of the most skilled fighters at this base, and he was the most skilled swordsmaster. He would probably be able to survive for a year if he joined the hero's party. If someone else went, how long could they last? A few months? What then?
To save his father, he would have to sacrifice many others. He did not want that, but he did not want to lose his father.
- The choice isn't up to you.
He started out of his reverie.
"You're right. I'm still a kid. He can decide for himself. But I think this is a question with thinking about."
...
The boy killed another small band of demons the next day. He stabbed and slashed at their vitals, killing some instantly while letting others slowly bleed and lose strength.
He huffed as he stood amidst a new pile of corpses.
He collected himself, then began dissecting them one by one.
In the same forest, a party of four ambushed another group of demons. They lured the creatures into a clearing and then bombarded them with magic until they died.
They were impatient and exhausted. They wouldn't be able to hold out much longer.