Zero the Knightmare Slayer

Some people would call Lelouch Vi Britannia many things: a liar, backstabber, tyrant, and others when he began his path of revenge. But what if He experienced someone else's life and knows that person's endeavor would make him a better person in life? This is how it Began.

Lelouch didn't know why but he was seeing something in a dream; it felt real in a sense. He could feel the soft touch, the smell of the forest, and the cold winter on his skin.

He saw five kids playing in the snow. Their hair was dark, not unlike his raven hair. They wore some old Japanese clothes, a kimono. He saw the oldest kid, a boy barely entering teenage wearing a green and black-checkered kimono, helping the youngest one shape a snowball.

He continued seeing the children play around with a smile. It reminded him of the past, before the Aries villa incident before the invasion. How he would play around happily.

Then he saw the boy selling charcoal in a small town, quite a little far from the mountain he was living in. The tone shifted when he saw a nice old man telling him to stay the night in his house for fear of man-eating demons; even he felt disbelief. In the end, the boy still rested in the old man's house for the night because he did not want to disappoint the old man for his kindness.

Lelouch didn't understand what he seeing; it was the Life of Kamado Tanjiro.

After resting and returning home, the boy's entire family was dead the next morning.

Lelouch woke up with a startled panic; it reminded him too much of what happened at Aries Villa as what happened to his mother and Nunnally. "Why do I have such a dream?" That was the question and it wasn't just that. He could feel the boy Tanjiro's feelings of guilt, suffering, and despair as if he was right there.

In school, he faked that everything was normal to others. But on the inside, he couldn't remain calm and felt nausea as the memory was still fresh. When night time came he was afraid to sleep, less he feels that same suffering again.

Even so, the nightmare continued. Lelouch saw the boy's surprise that his sister was alive. But instead of wallowing in pity, he took the initiative to bring his sister to help. Then surprisingly, his sister awoke as a demon and attacked him, both falling down a cliff.

An unknown person appeared and explained that his sister had been turned into a man-eating demon. However, instead of fearing his sister, the boy determinedly tried to protect her. Again, he felt a connection with the boy as even if Nunnally were turned into a demon he would protect her at all cost.

The newcomer called himself the Demon Slayer Corps, and his mission was obvious to lay the demon who was once human. The boy quickly try to run and defend his sister but failed in the last attempt just before his sister the demon rose to protect him.

This brought him thinking there was another possibility, so the demon slayer gambled by letting the boy become a demon slayer and training under a retired slayer Urokodaki Sakonji.

Lelouch woke up happy seeing that there was a way to save Nezuko, but the question was could he do it. Could he do the same to Nunnally? He didn't want to ponder on that.

And like yesterday he act normal.

In another dream, he saw how the boy trained himself to hunt demons. Not in vengeance, but to turn her sister back into a human. That... honestly made him very confused; it was like revenge was his second priority, completely unlike himself. But the training was harsh as Lelouch could feel the pain and exhaustion on his body as it felt real. The sweat, the bruise, and the suffocation. He felt it all.

Every time he woke up he could feel his body was as heavy as lead as if he was the one training in the dream.

He saw how the boy cut a big boulder into two pieces with the help of his senior's spirits. His teacher was reluctant to let him take the exam to enter the Corps, but still, let him go. There he decapitated the demon that brought dread to his teacher by eating his prior students, and in the end, he gave sympathy to the demon. He prayed that it returned as something else besides a man-eating demon. He was something else.

Lelouch woke again in confusion and doubt. His heart was taken back, but his mind couldn't comprehend why Tanjiro would care so much for the demon he slew.

Still, he had to go to school and act normal as usual.

In school during P.E. Lelouch was sitting on the sidelines until he was told to fill in for a basketball player. The old Lelouch would've made excuses, but his body moved on its own. And everyone was shocked seeing Lelouch the boy who avoids P.E. like the plague play as if he did so for years.

XXX

"Alright, you wanna explain when you started getting good?" questioned Milly Ashford with her arms crossed.

"It's complicated Milly." 'It's not like I can tell her that the dream was the reason why it happened.'

"Still you've been acting a bit weird lately Lelouch. I mean you always dozed off, but you never had the reflexes to grab chalk thrown at you like a baseball pro." Rivalz explained.

This time it was Shirley's turn to explain. "And don't forget the other day you helped the Drama club with their performance when one of the actors got sick, then you helped Sophia to the medical room when she sprang the ankle. And so on and on."

"Not that I'm complaining, but it's completely out of character for you," Milly said, knowing Lelouch personally.

"I wanted to try a different approach in life, that's all." That was his only explanation.

They weren't buying it. "But why the change?"

"I read a book about this person and I'm trying to empathize with him that's all," was Lelouch's simple explanation.

"I see, but don't make it a habit. So, can you help with the next festival-"

"Not a chance," Was Lelouch's reply.

XXX

Usually, Lelouch would be afraid to go to sleep, fearing seeing the tragedy. But he felt he needed this to understand something in his life. It may be a road for his living dead life. Ever since the death of Mariene, his life was in constant struggle. As he needed to grow up for Nunnally's sake, living a fake life as Lelouch Lamperouge was pathetic. His life was fake, his origin was fake, his everything was fake.

This time the dream was about the first 'mission' that Tanjiro had to undertake as his journey to return her sister into a human again began. He saw the boy, with his keen sense of smell, detecting the demon and fighting them. He shouted in worry when the boy in the green and black-checkered garb was being overwhelmed by multiple demons at the same time.

Then came Nezuko out of the box to help him fight the demon until they defeated it. Lelouch felt happy by how far Nezuko was willing to fight back showing how even she could protect her brother. It made him wonder if Nunnally would have done the same.

The boy in the green and black-checkered garb was taking a rest somewhere in a city this time. Suddenly he smelled the demon that killed his family, following the scent to find the monster masquerading as a human with his very own family. The demon turned some bystander into another monster to get away, and fortunately, the boy was helped by a female demon. One who would help him return Nezuko to normal.

Lelouch then saw how their sanctuary was invaded by two demons under orders from the progenitor. The boy used everything to defeat the two demons, even the consecutive Breath of Water stance he had never used before.

The dream continued for a month and Lelouch decided to test if this breathing style could work in battle if he must fight.

He breathed just like Tanjiro, leading to his body feeling stronger and his perception getting sharper than ever; as Lelouch ran, it felt like seconds but then he felt his body was very heavy and couldn't breathe that well anymore.

Even if his body changed during sleep, it was still not enough as he must gain through experience. In other words, training.

"I need to practice more using this to my advantage." The former prince smirked realizing what he could do with this power, but he needed to train, and it's something he didn't want to do. But he didn't have a choice granted he was given the power.

It wasn't just Tanjiro Kamado Lelouch would dream of. He even got those of others like the cowardly gigolo Agatsuma Zenitsu and his Thunder breathing. The boy was a coward but he exceeded such graceful swordsmanship that even Lelouch doubted him when first saw him. It goes to show never judge the book by its cover.

Inosuke Hashibira. A wild person wearing a boar masked that loved to fight. His brute strength was reinforced by the Beast breathing style.

Kyojuro Rengoku. An honorable person who always smiled and was optimistic to a fault despite a dark past. But he continued to move forward with his life with a smile and his Flame Breathing style.

The more he learned the more he understood what flaws were within him, as he was angry about everything that he would lash out. But he would assure himself if it was worth it. Would it be worth it to make a gentle world but hide it from his sister in a selfish way?

Using her as an excuse for his crusade in the name of a gentle world that Nunnally wanted?

He blamed everything for all the shit that'd happened to him including the Royal family. He couldn't trust anyone at all fearing being betrayed again, especially by his friends.

He once promised to destroy Britannia but he didn't. He only laid low and complained, because no miraculous power would come to his aid. But seeing Tanjiro changed him; instead of waiting for one, he would have to create one. He had to destroy and rebuild Britannia he needs connection and money.

But before that, he needed to go on a journey first, go back to where it all started as he once explained to Nunnally. The Kururugi Shrine.

When he arrived at the Shrine, he found it was a wreck. There were burns and wood splinters around the shrine. This was his home after being exiled. It wasn't the best place but it had many fond memories.

'I'm sorry I didn't come here. You weren't the best place to live, but you did have many good memories in my life. This is where I became a commoner and how I met Suzaku.'

Lelouch inspected the Shrine before spotting something sticking out of the rubble. As he looked closer, he saw it was a Katana. Pulling it out he examined the blade. It was beautiful metallic steel before it morphed. The color changed all of a sudden, just like a Nichirin Blade. But it didn't matter how or why. What mattered was that he had his resolve, and the Blade might be a guide to destiny.

As such he searched the Shrine more until he found a secret entrance. Curious, he went underneath where he found a secret chamber. It turned out to be a research lab that was used during the Taisho Era. Abandoned and forgotten, all that was there was a Mech design that used spiritual energy to optimize performance.

"Time to go to work." Unknown to him, something metallic was sticking out from the seaside.

Two years have passed after the dreams ended. Lelouch was going on with his fake life, but unlike his old self, he wanted to experience to the fullest of being normal. He once complained that living a lie was death, but understood how normal life was hard to get and how selfish he was. While those in the student council suspected something was different with Lelouch for starters he was more active and full of energy.

The first one who found out was Milly Ashford as both of them were close childhood friends; she saw how he was friendly to a few people and others on campus when usually he avoided them with a friendly smile, especially the female populace.

Sometimes he would help at the student council and other students with their problems and he was willing to listen.

He even saved Nina from the Eleven harassment that would have traumatized her, a gut feeling telling him she was in trouble. He even explained to her why as they did it out of spite after Britannia took everything from them including their culture.

XXX

There was one night in winter, Milly was curious that Lelouch and Nunnally were missing and decided to search for them. He found the siblings in the forest where the academy was. Bizarre was the word to describe what she saw where Lelouch was dancing in the fire wearing a strange eleven outfit. Nunnally and Sayoko were watching.

The dance was mesmerizing. It was something she had never seen before. It held beauty and style.

Lelouch taught her sister Breathing, the beast breathing style which was best for her as it enhanced all of her senses to the max and assisted in her legs' rehabilitation, a long time of work she managed to pull off through insisting. And all that hard work paid off.

After he told her about his dream, Nunnally realized that was the reason why he was different. Honestly, she was rather happy that he changed for the better, and the story while crazy was inspiring for her heart. Even though Nezuko was less outward, she was inspiring to say the least.

Besides Milly, someone else did come; Kallen Kozuki, alias Karen Steadfield by the public. Wandering the forest after a dispute with her brother, she was in anger. Being alone in the trees, Kallen could avoid anyone listening to her rant. It also reminded her of when she, Naoto, and Ohgi would go camping.

Then she heard a noise as such before she was attracted to the noise and saw a fire.

She saw Lelouch dancing in the middle of the snow watched by three people. Of course, they noticed her presence but didn't say anything as they watched the dance. She would scoff that a Britannia or someone, not Japanese was performing the sacred dance, but his movements were entirely professional; focused, and beautiful.

It's as if that person knew how to dance properly concerning the customs of Japanese tradition.

When he stopped he revealed his face for her to see. She was shocked to see that a Britannia boy of similar age was dancing. She felt out of place as everyone stared at her, and Milly knew who she was.

So she introduced herself as Karen Steadfield, concealing her terrorist double life, and questioned how a Britannia boy learned a Japanese dance.

All Lelouch said is: "I had a dream and wanted to learn about Japanese culture."

This small introduction boomed into a friendship and Milly decided to tell them that she was half Japanese and Britannia, the reason she acted sick to avoid anything connected to her being a hybrid.

Lelouch understood and accepted her along with Nunnally. She also shared her secret about how he was also a hybrid like her, between a noble and a commoner. She didn't need to know that he was the exiled and presumed dead prince Lelouch vi Britannia.

Milly used this to make her part of the student council later as she recruited Karen after the meeting that day.

It couldn't be said that Lelouch and Kallen weren't called close friends. She finally had someone she could talk to about Japanese culture without the trouble of prejudice, but she still hid her being a terrorist and Lelouch being an exiled prince vice-versa.

Sayoko, who was Lelouch's bodyguard, mother figure, and Ninja was also interested in learning the breath styles. It wasn't as hard to learn as she was a natural.

During his day he found two things in his life. One was a wrecker of a Knightmare blue and white with a humanoid size and horns. Lelouch found this Knightmare by chance; it might have been something a resistance tried to steal from Britannia. There was no news of a secret weapon stolen as the Britannia military wanted to save face that their so-called prototype weapon was lost because of their carelessness.

The other one was an amnesia person similar to his age found in the forest where he danced. His only name was Rai, and Milly along with Lelouch decided to help him.

XXX

Life still went on normally, but there were changes as some of those in Ashford empathized towards the eleven while others just the same. But it was there due to Lelouch's actions on how his enthusiasm and empathy spread.

It wasn't big, but some of the students had questioned Britannia's ideology. Right now he was in a Casino helping with the client and getting paid as right now he was on Rivalz's bike heading back.

That's when it happened. A truck crashed on the highway. Now a good Samaritan, Lelouch decided to help in what would be the turning point in his life.

"What are you doing here?" she asked after the truck moved. He then saw her face.

"I could ask the same thing! Wear your clothes properly."

Kallen blushed, screaming, "Stop Staring you pervert!" She got dressed quickly.

Looking at her dress and band, Lelouch realized something. "Don't tell me… you are a terrorist?" It wasn't surprising, but it did question so many things.

"Hey, we like to be called the resistance-" Then the shaking started again.

"We're being attacked, Kallen!" Nagata called back.

"Just give me a minute!" She climbed up the ladder. "And you stay! Don't get into trouble "

"More like trouble found me. But yes, you need to explain to me."

"Later!" In any situation, she would have put her blade at Lelouch's throat. But, maybe it was women's intuition or her heart, she felt like she could trust Lelouch for whatever reason.

The truck revealed her Knightmare frame and fired a slash harken on one of the VTOL. Destroyed, the chase continued towards the Ghetto. Then came the chaos.

XXX

Lelouch was surrounded by the Royal guard after the truck crashed and he was attacked by someone who turned out to be his best friend Kururugi Suzaku, now an honorable Britannia soldier. His mission was to secure Clovis' secret project, a green-haired woman in a straightjacket.

"Any last words kid?"

"Do you take pleasure in killing them?"

"Well of course! I love squashing insects."

"Then I won't give you a painless death."

"… what."

"First Form: Thunderclap and Flash." In just a matter of seconds, all of the royal guard members were slashed by their arms and legs causing them to bleed out on the spot. Lelouch had this sword with him all the time.

'How did he conceal such a weapon!?' Sayoko thought to himself.

"What are you!?" The commander fired his weapon, but Lelouch just deflected the bullets with his blade, the speed slower than the lightning breath he has spread through his lungs. He dashed and cut both the enemy's limbs.

"It hurts! Help me!"

Lelouch faced him. "Do you enjoy being on the receiving end of the pain?"

"This won't do! You will be hunted down for harming the Royal guard!"

"Doubt it. They would just think that a terrorist did it. Plus, you won't live to tell the tale." Lelouch walked away leaving the scum to die. His ears caught a sound and he quickly hid as a Knightmare emerged.

Villette, one of the purebloods, saw a pile of dead bodies. Her eyes spotted one of the Clovis royal guards barely alive. She quickly got out from her Knightmare before she blacked out as someone hit her on the head.

Lelouch struck her on the neck and quickly checked the Sutherland. "Dang it, needs a password." Well, he could hack.

He decided to wear the costume that he prepped to become a demon slayer but not before putting on a mask to hide his features.

"So, this is what you are going to do?" asked the green-haired girl that he had just forgotten about.

"I suggest you go somewhere safe. Whatever they want from you."

"Don't you want to find out why?"

"Not right now. I have more important things to do." He boarded the hijacked Sutherland. That caught her off guard. "Just go somewhere safe first."

The battle turned the tide during Lelouch's command as the resistance followed his instructions to the letter and took advantage. To him, it was like playing chess. The old Lelouch would have found it to be fun.

XXX

As of right now, he's facing the white Knightmare, a new model a fifth-generation maybe. "Either way, I have to beat it. But, I could salvage or capture it."

Lelouch in his disguise came out from his damaged Knightmare confronting his foe. Suzaku who was watching this was surprised by the boldness of the one causing terrorism to area 11. He was even wearing Japanese school clothes prominent during the Taisho era and a fox masked.

As he moved the Lancelot to grab the masked terrorist, Lelouch just jumped on top of the Knightmare arm using it as momentum as he dashed. "Eighth Form: Waterfall Basin!" Lelouch swung the sword vertically, cutting off the entire arm of the Knightmare.

If Suzaku wasn't shocked seeing it with his own eyes, he would say the pain being shot made him hallucinate. But the rumble and the warning sirens were real. That person cut him.

"Suzaku, what happened? The system said the Lancelot lost an arm!" Cecile called.

"What she said!" Lloyd pointed out.

"I'm sorry Llyod sir. I'm engaging an unknown enemy and it cut off the arm of the Lancelot."

"What! But how?!"

"Even if I tell you won't believe me!" Suzaku was searching for the masked terrorist looking around in panic. Then the Lancelot felt unbalanced before he knew that the person cut Lancelot's legs making him crash down.

Cutting it was easy as the person was still a newbie.

"Suzaku, retreat!"

"But I have to apprehend the terrorist."

"It doesn't matter; keep the Lancelot safe! That's an order!"

Suzaku hesitated, but ultimately complied as he didn't want the enemy to obtain the Lancelot technology. He fired a slash-harken with the remaining arm and used it as a grapple to escape from the war zone and the assailant.

Lelouch was surprised that the enemy Knightmare escaped, but it didn't matter. He managed to obtain parts of it and he was going to use it. He needed to call someone to pick it up.

"Rai, I need you to help me with something first," Lelouch then explained his condition and location.

"I'll be on my way."

"Good and I'm going to finish this." The line was off as Lelouch looked towards the command center.

Kallen never thought she and her friends would be cornered like this. They just wanted to capture the poison gas so that they wouldn't use it on their people. Instead, they got an instant massacre by the Britannia.

All of the soldiers were ready to kill them instantly until they heard on the radio the order to stand down. By Prince Clovis himself. Reluctant, they obeyed rather than having the wrath of royalty bring down their necks.

"It's done, so what do you want? A game of chess or something?"

"That would have been idle, just like in Aries villa."

Hearing that, Clovis was shocked knowing it could be him. But he had to make sure.

"I remember how we used to play with my mother and sister along with others." Lelouch pulled his mask revealing the familiar face.

"Lelouch?!"

"It's been a while Clovis. It seems you have changed these past couple of years."

"But how?"

"I survived during the invasion through cunning and hardships." His eyes turned harsh. "Why are you doing this?"

"What do you mean?"

"This massacre!"

"They are just elevens, Lelouch! Their lives are meaningless to us and they harbored terrorists."

"There's no excuse to kill them to keep your dirty secret about the girl!"

His eyes widened with the realization. "You saw her?"

"Yes. It was a green-haired girl in that capsule, and whatever reason you even forced the royal guards to kill me for witnessing it."

"Where is she?"

"She escaped somewhere."

"Then I'm ruined! If father knew about this I'll be disinherited or exiled!" The prince was in a panic.

Lelouch just looked at him with pity. "Clovis, what happened to you? Where was the man I knew who would paint with joy with all of us? The brother that painted the things I loved?"

"You don't understand Lelouch!" Clovis shouted in anger. "Ever since you were exiled things have changed in the palace; there were schemes atop of schemes and Merrybell lost her royalty after what happened to her mother and sister! We had to be ruthless to survive in the royal court."

Rather than being angry, Lelouch frowned in disappointment. "Clovis, who killed Lady Mariene that day?"

"All I know is that Schizel and Cornelia might be the ones."

Lelouch could tell Clovis wasn't lying through his sensitive ears. "Clovis, I'm just sad seeing what you become. I can't even tell Nunnally that you willingly killed all these people because of fear. You're no longer the same Clovis I grew up with."

Clovis was shocked seeing Lelouch's face as something inside of him was moved, a lock to his heart clicking open. So many of these forgotten emotions were returning. Lelouch had a gift that was similar to Tanjiro, being able to persuade others, making them realize their mistake, not running away from fear and such.

"You're right. I became something I despised, just like my father. I didn't even see it coming." He looked won in shame. "But even if I surrender, I will still lose everything. And I can't convince you to come as a way to help me."

"I would have killed you." Clovis just bitterly laughs knowing he was between a rock and a hard place

"No matter what outcome it will be the end of me."

"I know, which is why I'm going to end this and make it painless."

Clovis would have screamed in terror but something in his heart accepted that offer. "Killing me would bring the wrath of Cornelia upon this land."

"I know, and I'm willing to stop her."

Clovis just smiled sadly. "I wish we could go back to Aries Villa just like the old days." Clovis reminisce how their life was so simple that day.

"Me too brother."

"Swoosh!"

Lelouch got his answer to what he was looking for. Tears fell for Clovis one last time before he departed the Ghetto. This was just the beginning as his normal life would be gone and time to change the world.

The influence of Tanjiro's Journey made him understand his flaws and that he needed to change to be better than himself.

I think Nunnally is the right person to learn Beast-style breathing as it enhances her senses.

The Taisho mech was based on Sakura Wars.

Lelouch would never made a contract as he no longer desired such power and would fight his own way.