Summary: Alternate Universe: With winter on its way, the siege unrelenting, and resources running dangerously low, Senku has to make the choice to either come to terms with Chief Tsukasa for a ceasefire or see his people and friends perish. Tsukasa is fighting to keep the old traditions and the power of the gods, while Senku seeks to change the world with his advanced knowledge of science, alchemy, and astronomy. Neither wants to see the other succeed; Senku won't give up his science, and Tsukasa won't abandon his idea

One day, Senku sends his advisor, Gen, to discuss peaceful terms with Tsukasa for the winter. However, Tsukasa will not accept the offer of shelter for the winter, so Gen, in a desperate attempt to gain a truce, offers the prospect of marriage; Chief Tsukasa to Lord Senku. Despite being enemies, both men will accept yet each has their own agendas and plan to use the other to their advantage. They think the only traits they share are the safety and happiness of their people, but they may discover they have more in common than previously thought. Yet Senku will not give in to Tsukana's charismatic personality or the lurking wonder of possibly having a romantic partner, something he has sworn off and never had any interest in. Tsukasa feels the same; Senku is his enemy, after all, but a proud spirit can weaken over time, and taking Senku's throne will only help his tribe prosper. But being with Senku will prove to Tsukasa that there is more to science as well as the scientist behind it. His curiosity to know more about Senku may have him giving in first. Maybe.

But there is a rising threat outside the castle territory and it can either bring them closer together or push them further apart.

(This is a fanfiction of enemies to lovers slow burn with a happy ending: 25% mature, 75% teen/gen. audience) If you, the reader, have any worries or concerns about the tags, or just general questions before reading, please DO NOT hesitate to email me! My email is in my profile, and I will gladly clarify as much as I can. I want the reader to enjoy the story! ^_^)

A Year and a Day

By Tenkku

Chapter 1: The Lion and the Stallion

The siege lasted for a little more than a month before Senku had to make the difficult decision that he had been trying to avoid since the standoff began. Sitting at his desk in the laboratory chambers of the castle, he taps his forehead in deep thought while his eyes scan the numerous numbers written in one of the many ledgers. Supplies are low. Resources for continuing to hold off the siege are running out. The people, though still in high spirits, were becoming exhausted, and outside help is not coming.

Senku couldn't blame them. No one thought the siege would last this long. Tsukasa, the enemy, and the Army of Might had them surrounded, cutting off their access to the resources of the land. Though the castle borders the ocean in the back, Tsukasa's people have set up camps everywhere, including the shore. His fishermen couldn't get to the water. His hunters could not sneak out and find wild game. His gathering group could not go out and explore to find materials needed to fight back. All of them said they are willing to take the chance, but Senku had promised them when he became the leader of this place, which he coined the Kingdom of Science, that he would never let any casualties happen; not under his watch, if he can help it.

Getting up from his desk, Senku walks over to the barricaded window, grabbing his telescope along the way. His kingdoms' advancement in scientific creations, weapons, alchemy, and food preservation is what has let them hold off successfully for this long. Why would their enemy, the Tsukasa Empire, prefer to live a primitive lifestyle when they could live more comfortably and learn new things? He understood it but just thought it was unnecessary. However, Tsukasa did not see it that way; he views Senku and his kingdom as a threat, hence this siege, when they couldn't come to an agreement a while back. Tsukasa wants his head.

Looking through the narrow telescope, Senku uses it to scan the siege camp, looking for anything suspicious. He can only see the army camp beyond the castle's defensive wall from this window. Nothing different or out of the ordinary. Senku then goes to the barricaded window looking out to the ocean, searching for the same thing. His scope lands on none other than Tsukasa; the primitive King of Beasts, also known as the Amber Lion because of his great size, strength, and majestic appearance of amber eyes. There is no mistaking the lion skin pelt adorning broad shoulders and those thick, dark brown tails of hair that resemble a lion's mane; it IS Tsukasa. Senku grumbles under his breath at how ridiculous the tribal people were with their overzealous nicknames and titles of animals given to themselves. Sometimes, Senku thought, less is more. No one needs more than one title.

Senku's breath catches in his throat when Tsukasa suddenly turns to look directly at him, hard amber eyes narrowing. 'Does he see me?' Senku wonders. 'No, he can't see me from that far away- it must be a coincidence.' Still, Senku lowers the telescope to back away from the window and returns to his desk, smirking, while flipping over a small hourglass filled with sand. By the time the sand passes through, he will be ten billion percent sure of his final decision.

'I can't look at this ceasefire as a surrender or even a defeat,' he thinks to himself, watching the specks of sand trickle down in a tiny, foggy line. 'I'm sure I can convenience the others to look at this ceasefire as a necessity for the time being, and as time goes on, we can find ways to either bring the Empire of Might and Tsukasa to our side or find a stealthy way to attack from within, on our own grounds, in our own territory.' If anything, he can gather more information on Tsukasa and know where the man is at all times and what he is doing.

The sand finally piles at the bottom of the dial. He's certain of his decision.

Going to the door of his chambers, he asks one of the passing guards if they would fetch Gen for him. Gen is his adviser in these types of matters and often will take on the role of political leader while he is busy tinkering with science and alchemy. Senku often found the politics of his new kingdom and others boring and uneventful. He'd much rather find ways to strengthen his kingdom and the people residing than get involved with the politics of nobility. Humans can't progress if they are stuck in the old ways of polite tradition and etiquette instead of learning something new He often ignores the social gatherings of celebrations like balls or galas and will send someone else in his stead to represent him. Other times, his friends force him to go. He preferred if everyone would celebrate here in the castle. Senku didn't mind making merriment with his friends and people, but science is always his number one love and desire.

"You called?" Came Gen's lyrical voice from the open doorway.

"Yeah, I did," Senku rocks back on the two back legs of his desk chair, folding his hands lazily behind his head. "After looking over our number of dwindling resources, I've concluded that we will not be able to hold out any longer against Tsukasa. That's why I've decided to call for a ceasefire."

Gen's gray eyes widen in surprise as he folds his hands into his long bell sleeves and approaches Senku's desk. "A ceasefire? Do you honestly think someone like Tsukasa would accept that? He will want a surrender, not a ceasefire."

Senku grins at Gen, lifting his feet to cross his ankles on the desk. "I'm sure a talented mage such as yourself can help persuade him to see that this ceasefire will help both sides?"

Gen sighs softly. "While you are correct in our sources and food becoming less, we should not just give in so easily," he matches Senku's sly smirk with his own. "Just what do you have in mind, My Lord?"

"We make a deal," Senku started, "Both sides are exhausted, and autumn will be over before we know it. Everyone will need to make preparations for winter. We'll offer Tsukasa and his tribe to take shelter here during that time,"

"I'm sorry, Senku, but I fail to see how that will benefit us? Tsukasa wants you dead, or have you forgotten?"

Senku lets out a snort of laughter. "Oh, I haven't forgotten," he returns to a seated position, flipping the small hourglass back and forth between his fingers. "This is how I see it; I want to know where Tsukasa is at all times. What better way than to have him here? All of us can gather information about him and his tribe, things that can potentially help us in the future. Tsukasa is not anything but honorable in the end. He wants to see his people thriving, but by the old ways; by the 'gods' and the 'spirits' of the earthy world. I plan to charm his people with my great knowledge and skills of science, alchemy, astrology, and you know the rest," he tosses the hourglass in the air and caught it with one hand. "His people will want to flock to the Kingdom of Science, and Tsukasa will have no choice but to give up and give in. This way, we avoid casualties, further war, and any bloodshed. We'll make the enemy come to us based on the decision THEY make, not the other way around."

"My, my, such a well thought out plan that could have many different outcomes," Gen points out gleefully. "You want to let the enemy in by the front door and break bread at our table?"

Senku nods. "Precisely. We're exhausted, and they're tired."

"Hmm. Might I point out one small little issue, My Lord?" He tilts his head to the side with a mad grin. "How will you get him to 'share' the castle with you? There can be only one leader in Tsukasa's world, and that is him, not you."

"I've already thought about that too, Gen" he tosses the hourglass at Gen, who almost missed it.

"I'll make another deal with him. If he chooses to remain at the castle for the winter in peace, then I will show him and his people some scientific ways they can advance without it actually being science in the dark way they see it. Agriculture and ores are always useful no matter what level of living! He is not completely against progress and WILL put his people first."

"Hm…I still think we should take a day or two to consider this," Gen says. "You're gambling with the lives of our people."

"That's why I've appointed you to go and deliver our terms to Tsukasa," he says. "Your silver tongue can find a way to win him over better than I can,"

"Shouldn't you be there, too?"

Senku shakes his head. "I'll be here to greet him when he accepts. If anyone can convince him of this, it's you. I would take only Kinro and Ginro with you," he suggested. "They will protect you but also won't let Tsukasa feel threatened, leaving him more likely to listen to what you have to say."

"Am I to carry a white flag?"

"Hell no," Senku replied. "Take our Kingdom of Science flag. We're not surrendering. If you feel the need to, take Kohaku with you as well."

"And if he refuses everything?"

Senku chuckled. "I guess you finally doubt your abilities, then? Maybe I should find someone else to replace you,"

Gen chuckled as well. "Good luck finding someone with my level of mage skills! I know you only jest, My Lord. But I will see it done,"

"Thanks. And Gen, good luck!"

After Gen had left, Senku took a quick nap while waiting for his friends, mainly two in specific, maybe three, to come barging into his lab. Gen would have told his council what the plan is and they will have something to say about it. And Senku was right, of course. He peeks a red eye open when the door opens and Chrome comes in with Kohaku right behind as well as Taiju. Chrome is his fellow scientist and apprentice with a knack for collecting ores and minerals. Kohaku is the General of the troops and their strongest warrior. Taiju is his best friend from childhood and helps out with the hard labor due to the unnatural stamina he possesses. They probably couldn't notice it, but Senku recognized the expressions of exhaustion on their faces. With exhaustion leads to possible illness and lack of good judgment.

"Are you seriously letting him into the Kingdom of Science?" Chrome asks with a heightened tone mixed with shock and annoyance.

"I'm sure Gen gave you the rundown of what the current situation is concerning the siege," Senku stuck one finger in his ear. "At this point, we really have no other choice- it's either find a balance of power or give in completely. I choose the first one,"

"But we can still hold out for a bit longer!" Taiju protested. "Maybe they will turn around and leave because winter's on its way! And then we don't have to worry again until spring!"

Kohaku speaks next. "That won't happen, Taiju. Tsukasa's army has access to the ocean and hunting. If they wanted to, they could wait out winter here,"

"Ten billion percent correct," Senku tosses the hourglass to Kohaku. "We're stuck here, and before we all perish, I would like to settle this siege. I know everyone is exhausted; even our catapults and arrows are exhausted and need maintenance, which we don't have the necessary supplies for,"

"Senku, I know what you're saying is right," Chrome says. "But…I think you're putting too much trust in Tsukasa. And is it really wise to teach the enemy how to build things like weapons? OUR weapons?"

"My main objective on that front is to win over Tsukasa's people by showing them how much easier life can be with the power of science. Tsukasa will refuse to learn how to build our machines, but that doesn't mean his people won't want to learn. And living in a castle, which can be built onto and expanded, is ten billion times better than living in the woods, especially in the winter." He leans back on his chair again with a smug smile. "I'm anything if not hospital to my fellow man."

"You're just sneaky," Kohaku points out. "And I know you have another plan."

"Senku," Taiju walks around Senku's desk and takes his hand. "While I don't agree with it because it puts your life at risk, I do understand why you're doing it! You don't want anyone to die even though we have the means to wipe out the enemy without even lifting one finger! We don't want to see anyone lose their lives, friend or foe! I'm sure Tsukasa will recognize that and he will agree to this crazy plan! And if you say we should welcome them in, then that is what we'll do!"

Senku had to struggle to pull his hand out of Taiju's loving, bone-crushing grasp. "Don't get so mushy, you big oaf! And shouldn't all of you be doing something that's not standing in front of me flapping your gums?"

"Well, I'm not going to trust him that easily!" Chrome states firmly. "You should never be alone in the castle if Tsukasa and his tribe agree to stay here!"

"I'm with Chrome," Kohaku agreed. "You will need constant supervision,"

Senku rolls his eyes. "I'm not a child, you know. I'm quite capable of taking care of myself. If Gen hasn't left yet, then Kohaku, you should go with him. It wouldn't hurt to have a lioness' strength nearby when facing off against a lion- OW!" She had thrown the hourglass at his forehead but he was never offended, rather amused, by her reactions when he teased her. "You all know that I'm right," he says. "Let's hope that Gen's scheming skills can manipulate Tsukasa effectively."

At first, Gen thought about being carried out on a sedan chair by Kinro and Ginro, and then realized the show of flare would be too threatening; they needed to be humble right now. Then he thought about a horse, but again, he'd be looking down on Tsukasa from up high, which also wouldn't work. In the end, he chose to go on foot wearing no armor, only his daily robes, and cloak. He couldn't appear threatening if he is going to talk terms of peace. Gen knows this isn't going to be easy. At the first sign of retaliation from Tsukasa's warriors, Gen told Kinro and Ginro not to fight but only defend and make their way back to the safety of the castle. He wouldn't be doing this willingly if he didn't believe in Senku's plan, even if the man had missed the 'luck' handouts and received double the intelligence instead. Bad luck seemed to always follow Senku.

"You should let us go first," Kinro suggests to Gen once they are at the iron gate.

"M-Maybe we should put him in the middle!" Ginro offered, trying to keep the tremble from his voice. "I volunteer for the back!"

Gen gives his answer while watching the iron gates pushed open. "I say we go with Kinro's suggestion," he says. "We want to show that we are not posing as a threat, but that we have something of great importance to say. And, considering this siege, the Amber Lion should have no want or reason to attack us."

"I can't say I fully agree with Lord Senku's plan," Kinro states firmly. "But the rules are the rules, and if Lord Senku says so, then it shall be done!"

As the three approach the enemy siege camp, Gen starts to find it difficult to keep a calm, friendly smile on his face once the hulking tribal warriors start to slowly gather, looking fiercely at them. Gen glances back at the castle towards Senku's window, knowing that the other is watching through the telescope. Keeping his composure, Gen intakes a small breath of air before addressing the warriors.

"There is no need to raise your weapons to us," Gen starts. "We would like to speak with your chief if you would retrieve him for us? I have a message from Lord Senku that I must deliver to him."

"I'm already here,"

Gen feels a shiver run up his spine as Tsukasa appears from the crowd of warriors to stand before him. Kinro moves closer to Gen's side, his spear ready to defend while Ginro keeps one step behind.

From the window, Senku focuses his telescope on Tsukasa's tall, hulking figure looming over Gen. Senku has yet to meet a person that matches Tsukasa's height and build. If he were to believe in the gods that the tribal people believe in, he too would assume that Tsukasa was perfectly crafted by divine hands. But Senku knew the truth- Tsukasa was just a man born like any other who happened to have a godly physique with brute strength and handsome features. Senku paused at the word 'handsome'. It's not that he thought the Amber Lion was handsome- that's just what others say about him. Tsukasa is also known to be intelligent, unlike other tribal folks, so the chief WILL see reason.

"How's it going?" Chrome asks from behind. "Can I see?"

"Nothing is happening," Senku answered. "Gen is talking to him now with that winning smile and silver tongue,"

"I still have my doubts about this plan of yours, Senku,"

Senku grins and lowers his telescope to look at Chrome. "Don't worry, I have everything under control."

"So, those are the terms that we are offering you," Gen finished relaying Senku's message. "I think it is fair to say that we are all exhausted and it is time for some change?" Gen's insides feel like a swarm of butterflies as he awaits Tsukasa's answer.

"Your master, Senku, wants us to reside under the same roof where he conducts his science and other unearthly atrocities?"

Gen nods. "Yes. However, do keep in mind that this is not a hostage case, nor one of conquest,"

"Hm."

"Surely, living in a fine castle such as ours for the winter would be a godsend for your tribe," Gen points out. "And do not fret- all are welcome in the Kingdom of Science, so you may bring your gods and other traditions with you. What do you say?" Tsukasa slowly closes his eyes as if thinking, then opens them a second later. Gen gulps.

"Your master offers gracious terms of surrender,"

Gen chuckles. "Oh, it's not surrender, Chief Tsukasa! It is a ceasefire, remember?"

"I will not accept a ceasefire," Tsukasa tells him. "Either he surrenders to me and becomes my prisoner, my ward, and abandon science altogether, or we continue this siege and his people will not survive the winter."

Gen frowns at that. What else can he do? How can he persuade Tsukasa to accept this ceasefire? "Would you give me a moment, Chief Tsukasa?"

Tsukasa nods.

Gen ushers Kinro and Ginro to huddle closely with him. "I fear I am out of ideas," he tells them. "Do either of you have anything to offer?"

"Wahhh!" Ginro whines in a whisper. "We're going to die this winter! It's over for us!"

"Nonsense," Kinro hisses at his brother. "We will not give in to the cold of winter! Gen, the tribal people are very traditional in old ways. Perhaps we can offer them something that is common in their culture to appease them?"

Gen becomes intrigued by Kinro's words, and that sparks an idea. It's an idea that will send Senku over the edge but with the right words, Tsukasa will accept their terms. "Okay, I have our trump card," he tells them. "If I get thrown in the dungeon by Senku, be sure to slip me the key,"

Ginro and Kinro look at him with confusion as they break the huddle.

Gen spins on his heels and offers Tsukasa a bright, winning smile.

"We do have one other option to offer you!" Tsukasa appeared to be growing impatient, so Gen came right out and said it. "We propose a marriage! You, Chief Tsukasa, to our dear Lord Senku!"

Kinro and Ginro's jaws drop open as both could not believe the words that had just come out of Gen's mouth.

Tsukasa's hard expression seemed to soften a bit. "Marriage?"

"Indeed! And we'll do it in the traditional way of your people," Gen says. "A year and a day! If both of you can enjoy each other's company for that time, then the marriage will be official and there will surely be peace throughout the region!" He steps closer to Tsukasa with a dark, mischievous look and beckons the large man lower so he can whisper to him. "You speak of conquest, right? Well, there is more than one way to conquer the enemy, without bloodshed or scheming or dirty tricks OR surrender."

"You're suggesting that I marry your master…without him knowing of it first," Tsukasa points out. "Should you be offering such terms if you haven't talked it over with him?"

Gen knows Tsukasa is right, but he wasn't done yet. Senku is going to punish him for this, probably with that strange itching powder. "I want to get your opinion first," he continues. "As I'm sure you already know, Lord Senku can be very stubborn despite having a kind heart and a good soul. He is always sought after and admired by both women and men. Our lord is always getting suitors, but he always turns them down. A man like him thinks that all there is to life is science, which leaves him no time for romance. But wouldn't it be a superb conquest to win over not just the Kingdom of Science, but also your enemy? A conquest of the heart is more romantic, is it not?" Gen adds a dreamy sigh. "Oh, unless you are not up to the challenge of winning my lords' heart? I wouldn't blame you if you were hesitant about that. So many have tried,"

"And what makes you think that I have any hesitation?"

"Well, you are a king of beasts," Gen points out. "Hunting dangerous wild animals is one of the traits you are known for," he says. "But it's easy to conquer a wild beast that only has strength on its side."

Tsukasa gives a soft scoff. "You seem to think I am nothing more than a barbaric, mindless oaf,"

"No, far from it," Gen tells him. "I'm simply offering you something more; something that is more of a challenge, like taming a wild stallion who refuses to relent. My master is that type of wild stallion- beautiful to look at, wild, independent, intelligent, but very stubborn and difficult. However, once you have the wild stallion eating sugar cubes right out of your hand, it becomes a companion."

"I'm not sure how to take your offer," Tsukasa says. "Again, you seem to be surrendering your master without his consent and already claiming that I can conquer him and his kingdom," he frowns deeply when Gen wags a finger at him.

"Uh, uh, uhhh," Gen says teasingly. "Have you ever seen a wild horse trample and kick their predators to death?" His teasing smile turns to a dark smirk. "Not all animals need fangs and claws to be dangerous."

Hearing that, Tsukasa can't help but reveal a small smile on his lips. "Hm. Very well then. I accept your terms of marriage to your master. However, I have a request of my own; you must return to your master and tell him of this, as you have offered it without his permission. Then, you can return with his answer. If he agrees, then a year and a day contract will be written up between us. If he refuses…I shouldn't have to tell you what will happen after that?"

Gen bows deeply to Tsukasa. "Oh, I assure you, Chief Tsukasa, that Lord Senku will accept this marriage proposal for the sake of his kingdom and the lives of everyone, including those of your people."

"Then I await his answer," Tsukana says, bidding Gen a 'good day' and heads for his tent. While walking, one of his men approaches him. "Do you have a concern?"

"Chief…what if this is a trap?" the man asks. "They could be luring us in there to slaughter us!"

Tsukasa smirks. "That's not Lord Senku's way," he assures the man. "He wishes to avoid any causality, as do I," he says. "The life and safety of my tribe are just as important to me as Lord Senku's people are to him. With winter coming, our people will flourish and grow stronger with proper shelter like that of the castle. We'll have to work out the details for those who will reside in the castle, in the barracks, and back at the village."

"And, you really think this marriage will work? What if he turns you into a frog or a rat with that magic science of his?"

That makes Tsukasa laugh. "Again, Lord Senku does not practice dark magic or any magic. It is science, but science is unnatural and it can only light the greedy ambition of people who want to conquer and destroy all that is natural. I'm not claiming it would be Senku or his people, but rather their descendants. Do you understand?"

The man hesitates for a moment, then nods. "Yes, chief. I will tell the others."

Tsukasa looks back at the castle and thinks about what it would be like to sit on Senku's throne. A marriage between them would be useful at this time because one of the other tribes and their chief, Hyoga, has been stirring up the idea of taking over the territories as a Chief Supreme. Hyoga's tribe would have to stay where they are for winter and attempt to carry out their attacks (if at all) in the spring. Having his people grow stronger during the winter will give them an advantage over Hyoga's forces. He does not want to revert to Senku's science for aid, but having that stronghold, along with Senku's own warriors like Kohaku and Kinro, Hyoga would have to give up or face the agony of defeat. No doubt word of their 'engagement' will reach Hyoga's ears and perhaps the chief won't even bother to attempt any kind of civil war.

"I guess we will just have to see what Senku's answer is," Tsukasa says to himself.

"Ten billion percent NO!" Senku almost shouts at Gen when his advisor brought the news of marriage. "Do I LOOK like someone wants to be married?"

Gen smiles nervously while Chrome and the others all stand behind him in shock, awe, and even with a bit of fear.

"But…it's merely an engagement," Gen tells him. "For one whole year and a day! Think of all the time that gives us to make a plan to defeat Tsukasa, and he'll be right here in the castle, just as you wanted!"

Senku crosses his arms and narrows his red eyes at Gen. "Gen, Chrome, Kohaku; you three stay. The rest of you can leave for now. I need to discuss some things with my advisor here."

Gen only smiles and as the others are leaving, he says, "You know I'm right in every way about this,"

Senku turns his back and says nothing. Gen did his job, and he did the job well, even if he doesn't agree with it. How is he going to make his way out of this ridiculous arrangement and still obtain the results that he desires? It would seem that Gen's logic had him backed into a corner at the present situation. Senku could sense the others were growing anxious at his silence.

"Senku, are you alright?" Kohaku asks. "Do you want me to go and tell Chief Tsukasa that the offer is denied?"

"No, not yet," Senku says, finally turning to face the others. "Gen, you can tell the Amber Lion that I agree to the terms,"

The three are collectively shocked by Senku's answer.

"BUT, I have a few specific terms of my own to relay to him first," Senku flashes them a smug, mischievous grin. "Get some parchment and ink! And Gen, you better not miss one word I say, for I will only say it once!"

TBC