The Youngest Son of the Northern Grand Duke Decided to Divorce

1

The Northern Duke sought to raise a heir capable of inheriting his title.

Of course, the title was merely a ceremonial honor, and a commander capable of ruling the northern territories had to be chosen.

A title alone could not lead the northern army, nor could it stand against monsters and barbarian tribes.

“…He collapsed again?”

“Yes. He overexerted himself using magic and collapsed.”

Tina Radiant, the third daughter of the Radiant Ducal House, answered demurely.

Her youngest brother’s talent had already been proven, but he was too frail to withstand the flow of magical power.

He had tried in various ways, but still could not overcome his congenital limits.

“I’ve told him countless times to take care of his body, but he never listens.”

“He must not want to stay that way. He must think he has to try something.”

“What if he dies from this? Who will you blame then? Not all problems can be solved with effort.”

Zaire Radiant, the head of the Radiant Ducal House, sighed deeply, his expression twisted with concern.

He had struggled to have a youngest son, but who knew he would be so weak?

Since childhood, he had often collapsed, and in serious cases, even bled.

Now, even walking slowly seemed like a miracle.

“I know, but… I wish you could understand Alter’s feelings a little.”

“Understanding won’t change anything. Your brother can’t do anything. He can’t even eat properly, let alone exert himself. And you want to leave him be?”

“Father. But we can’t just do nothing.”

“Alter must do nothing. If he wants to save his life, that’s the only way!”

“…”

Tina hesitated for a moment, then fell silent.

She wanted to defend Alter’s actions as much as possible, but she couldn’t deny her father’s words.

Her brother, Alter Radiant, was overwhelmed even by the task of preserving his own life.

“It’s good that he has a talent for magic. If he wants to learn on his own, I can support him as much as needed. But that’s not the point. He could die right now, so should he be preoccupied with magic?”

“Right now, the family can protect him, but later, he’ll have to live on his own. Then, it would be better to have learned some magic…”

“That’s why we arranged a political marriage with the Duke’s family. Isn’t the capital better than this place? The Duke’s family could use their connections to find medicine or a priest. I’m trying to save your brother’s life!”

Zaire raised his voice, quite agitated.

He had been worried about his youngest son, so he had not sent him outside the castle, and had even excluded him from simple training.

All he could hope for was that the fragile life would not be cut short.

But she knew she couldn’t protect him forever, so she had to look for a new way.

“I understand what you’re saying. But I’m a bit worried. That lady is… I mean…”

“Do you want to say she has a bad personality?”

“It’s not something to boast about. Even if we overlook her being a knight, there are rumors of her being hot-tempered and boisterous, right?”

Tina viewed her brother’s fiancée with disfavor.

Even if she was a lady of the ducal house, her conduct and character were nothing short of scandalous.

If her youngest brother married that lady, she feared he would be tormented for life.

“They know what they’re getting into. Everyone has their shortcomings, so let’s just let it slide.”

“In terms of noble rank, our father is higher, isn’t he? I don’t think we lack authority or wealth.”

“The Elenath ducal family is a powerhouse in the capital. They’re still a major faction and haven’t opposed the royal family. With that kind of influence, titles are meaningless.”

“I’m not sure if they’ll treat him well. They could look down on him for being frail.”

“It’s a marriage of convenience between a grand duke’s family and a ducal family, isn’t it? If they’re rude, they’ll only be hurting themselves.”

Zaire had already grasped the general conditions and interests at stake.

The Duke of Elenath wanted to extend his influence beyond the capital, and he needed to find a noble ally within it.

Despite the clear flaws in each other’s children, a marriage of convenience would not bring any complaints.

“But still… I wonder if Alter can endure it. He’s going to a strange place to get married, after all.”

“Your brother probably knows as well. He’s weak, but not foolish.”

“…When do you plan to send him?”

“Sooner rather than later. Staying in a good place might help him improve.”

“I guess I’m next.”

Tina was already engaged to the heir of an earl’s family.

Unlike her youngest brother, her marriage was strictly a strategic alliance for the family’s benefit.

She might not be entirely content, but at least her fiancé had a decent appearance and polite demeanor, which was somewhat comforting.

“You both will live in the capital. It might be a bit bothersome, but… take care of your brother. And explain things well to your fiancé.”

“You don’t have to ask. I was going to look after him anyway. I can’t just leave him alone if he’s marrying such a lady.”

As always, Tina was conscious of her youngest brother.

Had his body been stronger, he might have become a great sorcerer who could shake the empire.

But now, he had lost his confidence and, with an introverted personality, he was making only feeble attempts to try.

‘Poor little brother. If only he could get a little better…’

***

Instinctively, I opened my eyes, but the scenery had changed.

I had certainly tried to use magic just a moment ago, briefly manipulating mana.

But in an instant, my vision darkened, and I was seized by a sensation as if my insides were entangling.

‘Just from using this much mana…’

The youngest son of the Radiant Ducal House, Alter Radiant, suddenly became aware of his reality.

Originally, the character Alter Radiant was supposed to die, and the protagonist would naturally break off the engagement.

However, Alter Radiant was still alive and moving, and I found myself inhabiting his body.

‘So the original owner of this body is already dead, and I’ve taken his place?’

Alter roughly grasped the sequence of events and tilted his head in confusion.

Originally, Alter Radiant was a character briefly mentioned at the beginning of the original work.

Alter Radiant’s death was a change that would affect the protagonist, essentially a condition for the story to begin.

‘… Why? For what reason? What does it have to do with me?’

Alter was quite perplexed, but he had already resigned himself to his fate.

He had become Alter Radiant and was still alive and breathing.

From now on, he had to overcome the inevitable destiny that came with being Alter Radiant.

‘Right now, the protagonist isn’t what’s important.’

Alter struggled to rise and clutched at his left chest.

His heartbeat was unstable, and his muscles had stiffened.

Even light movement was burdensome, forcing him to acknowledge his own frail state.

‘Can I be this weak? What’s going on?’

Of course, even before manifesting magic, his physical condition had deteriorated.

Walking was fine, but trying to run would immediately make his legs wobble.

A faint chill was enough to raise goosebumps, and his skin felt as if it was freezing.

How could one possibly cling to life with such a body?

‘It must feel like this to live because I can’t die.’

Alter slowly regulated his breathing and moved his legs one at a time.

His heartbeats still seemed twisted, but not enough to feel painful.

Above all, the mana overflowing from within sustained his entire body.

‘… Am I alive because of mana?’

Alter inadvertently came to understand the principle behind it.

A typical body would base its actions on bones and muscles.

But his body was so frail that the bones and muscles couldn’t function properly.

That’s why he had to support his bones and muscles with immense magical power.

‘Does that mean my organs are also powered by magic?’

If the body is weak, naturally, the organs inside would be weakened as well.

Even a single organ’s failure could greatly impact the sustenance of life.

In the end, to survive, he had no choice but to forcibly activate the functions of his organs.

‘If one is talented, such things are possible, I suppose.’

Alter managed to barely get out of bed and stood up.

His body felt creaky, but it was still bearable for now.

He had thought about trying out some magic, just in case, but who would have thought he’d faint on the spot?

‘With this body, I can’t do anything. Breathing is all I can manage.’

It was then that Alter began to envision his future.

Since he hadn’t died, he wouldn’t break off the engagement with the protagonist.

Meaning, if time continued like this, he would inevitably have to marry the protagonist.

‘That can’t happen. There’s nothing good about interfering with the protagonist.’

Alter didn’t want to intervene in the original story.

If he didn’t interfere, all characters and events would proceed smoothly.

But now, his existence would act as a variable, so he had to confront the protagonist somehow.

‘I have to break off the engagement… But how do I persuade?’

After pondering for a moment, Alter quickly came to a simple conclusion.

The Duke of the North must be pursuing a political marriage for his own safety and the family’s benefit.

Then, perhaps all he needed to do was to change that process.

‘It’s better than marrying the protagonist. I don’t want to compete with those talented guys.’

***

Zaire encountered Alter before dinner started.

Alter was already at the dining hall, and just as the eldest son and second daughter entered.

Since an accident had occurred, he had no choice but to warn Alter.

‘I’ve told you time and again. Do not use magic. It will only hasten your demise.’

‘Yes. I apologize for causing you concern.’

Alter responded politely, glancing around discreetly.

He had already been nagged to death by his other family members.

It seemed that Alter Radiant was receiving a lot of attention and affection from his family.

“…I have something to say, may I have a moment of your time?”

“Now is fine. Speak comfortably.”

“I wish to break off the engagement.”

“Hmm?”

“…”

The eldest son and the second daughter reacted immediately, but Zaire remained silent.

Alter was frail in body, not lacking in judgment.

He must have a fitting reason to mention breaking off the engagement.

“…There’s nothing good about breaking off the engagement now. You need to be at least a duke to move around comfortably. You’re not unaware of this, are you?”

“It’s not that I don’t want to marry. But to change my marriage partner, I must break off the engagement first, mustn’t I?”