Even for a succubus who has lived for many years, nine years went by in the blink of an eye for Merlin as she observed her primary source of interest training with his little sister.

Before she knows it, the little boy she officially met nine years ago at Uther's Castle has grown into a splendid young man, possessing a body that, while barely taller than an average man in his twenties, had a beautiful form and developed to the point it wouldn't lose to the body of a veteran knight.

She missed the days when Kay was smaller than her, allowing her to easily tease him, but she didn't mind seeing him grow up so much that he ended up towering over her as it brought a new dynamic in their relationship with Kay who started to tease her back in ways he wouldn't have done in his youth.

However, if there is something that has not changed for the succubus, it would be her interest in the young man's mysteries, which she had not managed to figure out.

His abilities to block her perception of him through her Clairvoyance, or to stop her from seeing and intruding into his dreams, or his ability to spirit swords which called his weapons, a feat she could only see as Magic, and not Magecraft because of its bizarre nature.

Despite the nine years that have passed, she has never been able to unravel the mysteries surrounding her abilities, no matter how hard she tries. But she didn't care for the slightest as she enjoyed the prospect of solving the puzzle that he is.

One night, as she stargazed with the two siblings, doing her job as Artoria's mentor as she taught her how to predict the future by reading the stars. But just like how she didn't manage to teach her Magecraft as the girl quickly gave up after half a year, she wasn't able to teach her astrology, much to her amusement.

And so, their daily night lessons quickly became their little hobby instead.

"It looks like she fell asleep..." Kay whispered when he saw Artoria sleeping on the ground, a little smile on her face, holding the hem of his shirt tightly.

"Seems like it..."

As she snapped her fingers, a blanket appeared out of nowhere before falling over the three of them, shielding them from the cold winds that swept through the rural lands. Then, she laid her eyes on Kay and started observing, an uneasy feeling in her chest.

For the succubus that Merlin is, that was the greatest mystery she found about Kay as he was somehow able to make her manifest feelings on her own.

Even if she was a half-succubus, she was still one, a female demon who doesn't possess emotions of their own. So, they feed off of humans' dreams human mind activity to harvest their emotions and use them as fuel to feel emotions themselves.

However, while Merlin could essentially understand human emotions by doing this, she can't really empathize with them because to her, those emotions were nothing but foreign to her as they all originated from others.

One of the reasons why she kept performing her pranks to others was because she wished to experience herself the feeling of amusement, the feeling of joy. But the only thing she received from her acts was the alienation of others, vivid emotions of hatred and annoyance from them, but nothing from herself.

Although she didn't care about people's feelings or opinions towards her little experiment, she wouldn't deny that she enjoyed provoking all sorts of reactions from others.

And then, she met Kay whose existence was an odd one, which is the main reason why he attracted her so much that she focused her sight on him instead of humanity. And just as they spent time together, she found herself surprised when she started to feel joy from being by his side, that she was happy, even though she hadn't used any emotions she stole from others as fuel.

She didn't understand how or when it happened.

Was it after they started teasing each other? After having a meal, eating the succulent wild boar meat Kay cooked with Artoria on one of their stargazing nights? After seeing him hit puberty and show his first sign of sexual growth? Or was it after she witnessed by accident Kay having his first morning wood when she observed him in his sleep, seeing how his little boy matured into a magnificent sword that wouldn't lose in size, shape and in hardness to an adult's.

She didn't know. But if there is one thing she has understood, it is that Kay has managed to arouse in her feelings that no one has been able to do before. And this fact interested her very much.

"Why are you staring at me like that? Is there something wrong?" She heard Kay speak, snapping her out of her thoughts, before she saw him looking at her with a frown, not out of anger but of concern.

After spending nine years by his side, even without her succubus power to see his emotions, she learned to read his expressions and prided herself about the fact she could now read him like a book, though she is often mistaken in her assessments.

"I noticed it for a few weeks now but aren't you losing sleep?"

"It's because I'm a growing man, I need to sleep a lot if I want to grow nicely." Kay said with a grin which quickly disappeared when he noticed that Merlin wasn't smiling. He then let out a sigh and looked at the starry sky with a serious expression.

"Don't worry about it, it's only temporary. It'll be over soon..." She heard him say it but she wasn't easily convinced.

"You know, if you let me intrude in your dreams, I could fix that problem for you." She said words she never thought would come out of her mouth in her life, but she didn't care about that detail as her mind only focused on Kay's state.

'What... is this uneasiness?'

"No, it's fine. It would be awkward for me if you saw things I don't want you to see."

"Like your erotic dreams?" She jokingly said, making Kay chuckle before they both looked at the sky until they noticed Artoria sneeze in her sleep, her body shivering a bit.

"I guess it's getting chilly. We should go back now." Kay said as he stood up and softly carried Artoria in his arms, the girl moaning in her sleep at the movement before she snuggled her face against Kay's chest.

"It looks like she's as pampered as she was in her youth. I will blame you if Artoria becomes a tyrant demanding your affection in the future."

"As if. She's not a child anymore, so I believe that she'll grow out of that phase soon enough." Merlin couldn't help herself but to giggle at his words as she knew, thanks to her power, how deep her affections and admiration for Kay were.

'Well, Artoria herself doesn't understand her own feelings, which I'm not really surprised about since she was raised as a man by Ector and his wife, considered and treated as one by everyone she knew with the sole exception of Kay who kept treating her like a girl, no matter how many time he got scolded by Ector for doing so. She doesn't really understand that she appreciates being treated as a girl by Kay, even though she knows it was against what she was brought up for, to become a king to lead this country. Still, this is quite interesting so I'll let it pass... I wonder how things will turn out if I give it a push...'

"Hey, do you want me to join you in your bed tonight? I'm sure you'd be happy to have a woman snuggle up to you on a cold night like now."

"Sure, as long as you don't molest me in my sleep."

"What will happen if I do?"

"Then don't be surprised if my hands wander around. Apparently I move a lot when I sleep."

And as they shared a laugh, they returned to his house with Merlin, the girl excited to see what kind of adventures they would have the next day.

However, her expectations were denied as Kay did not open his eyes the next day, spending the whole day sleeping and could not be roused no matter what.

"Great Magus, do you have an idea why this is happening?" Ector asked her as they both watched over Kay's sleeping body, along with his wife and Artoria who were kneeling near the bed, a worried expression on their faces.

"I don't know. I don't feel anything magical affecting him, so it can't be the effect of a curse or anything related to Magecraft." She said after closely examining Kay to find nothing abnormal, much to their concern as they all looked at the young man with anxiety in their eyes.

Ector fetched a priest from the local church who had knowledge about medicine, but he couldn't find anything abnormal from Kay's body. He then left in a hurry when he was told that a group of bandits were seen nearby the village, prompting him to go take care of them.

His mother stayed with them until it was time for her to go to the field, trusting the succubus and her foster daughter enough to take care of her son, despite her own worry.

And so, Merlin and Artoria were left alone in Kay's room, watching over him until nightfall.

"Artoria, it's getting late. You can go back to your room, I'll continue watching him." Merlin muttered to herself when she saw Artoria nodding off and let out a sigh when she approached the girl to see her already sleeping.

"Good grief... You siblings love causing trouble for others, not that I'm one to talk." She said as she carried Artoria in her arms and took her to her room, then she went back to see Kay in his room, still sleeping.

As she looked at his face, she could only let out a small smile.

'Even though it's been only a day, why does it feel longer than the nine years we spent together...'

"Hey, Kay. I think you had enough beauty sleep for today, so how about you wake up already? Everyone (I am) is worried about you, you know? All those people you helped in town those last few years, when they heard about your condition, they all came to visit to see you. They even left some get well gifts too, so you have to wake up. You can't make them (me) worry forever. If you don't wake up, I'll play a prank on you..." Merlin said before she blinked when she felt something wet drop from her eyes.

'This is... Am I crying? And this pain in my chest... I don't like this...' She thought as she clutched her chest, feeling as if she got stabbed through her heart.

But the succubus herself didn't know that she was experiencing her first feeling of sadness, of loneliness. Because she learned about happiness from her interaction with Kay, she now felt lonely for the first time as she was deprived of what she craved the most, spending time playing and adventuring with Kay.

Without thinking, she climbed on Kay's bed before straddling the young man and bringing her face close to his, their nose slightly touching.

"Kay... if you hear me, if you are trapped in your dream, let me come help you... so please..." She muttered as she brought her forehead against his and tried once again to intrude in his dream.

'I miss you...'

Then her mind darkened with her body falling on the bed, like a puppet whose strings had been cut, lying on top of Kay with tears streaming down her beautiful face.

When Merlin opened her eyes, she was surprised to see that she wasn't in Kay's room anymore.

"Where am I? That sensation… Am I inside Kay's dream?" She muttered at herself as she looked at her surroundings, seeing a vast expanse of water and cosmos with spectral butterflies gracefully fluttering around her.

'It's beautiful...'

She couldn't help herself but to be mesmerized the sight, but then, she heard the sounds of metal clashing against each other along with an immense amount of Magical Energy, making her widen her eyes before she turned in their direction to see Kay fight against a knight she guessed was the source of the Magical Energy.

"Kay!" She screamed as she flew in his direction, making Kay glance at her when he heard her voice.

"Merlin?! So, it was really her voice I heard just now..." He muttered as he focused his attention back to his opponent before he let out a shout. "Don't interfere, this is my fight!"

"...What?" Merlin stopped in her tracks, surprised by his words before she noticed that there were six corpses in their surroundings, all similar to the one Kay was currently fighting against.

'Was he fighting against all seven of them since last night?' She thought as she looked atKay who was covered in cuts and panting continuously, a sight she never saw in the real world, telling her that the fight going on was a harsh one. And as she looked worriedly at Kay, she saw him duck below the knight's swing, barely dodging the knight's sword as she noticed some of his hair being cut, before he thrusted his spirit sword into his opponent's chest.

"Did he do it?" She mumbled before she saw Kay, with a swift movement, swing his sword upwards with the blade slicing through the knight's body from the chest to the top of his head, before he fell to the ground, defeated.

"Yes... I finally beat those sword gods!" She heard Kay scream before she widened her eyes when he suddenly fell on his back, prompting her to rush to his side.

"Kay, are you alright?!"

"Ahaha. Yeah, I am... Still, it's weird to see you worried..."

"It's your fault, you idiot." She said as she slapped the young man's forehead who chuckled, but before she could ask him for explanation, she felt her mind drift away, telling her that Kay was going to wake up.

"You better explain everything to me once we're outside, am I clear, mister?" She said to Kay who slowly nodded, making her smile genuinely as she held his hand. Then, they both left his dream together.

When Merlin opened her eyes once more, she woke up with the sight of Kay's face being close to hers, smiling at her with an apologetical expression on his face.

"Sorry, it looks like I worried you."

"Don't go stating the obvious. You spent a whole day in your dream fighting whatever it was. Don't you know how much you worry everybody?"

"Again, I'm sorry. I'll do my best to repay this debt."

"You better." Merlin said as she suddenly brought her lips to Kay who widened his eyes in surprise before he closed them and kissed her back, to her joy and pleasure. And after staying like that for a few seconds, which felt like hours to the succubus, she then straddled him and quickly took off her clothes, throwing them on the floor.

"And don't you think you're out of this mess yet, I'm going to make you pay for making me worry like that." She said, as if announcing a matter of fact, before she was surprised when she felt something growing larger and harder under her crotch, making her smile smugly at Kay who looked bashful.

"Do you mind if we go elsewhere? I don't want Artoria or my parents to wake up if we make too much noise."

"Sorry, but no. I won't wait a second. Don't worry, I'll put a Bounded Field around your room, it'll make it soundproof so don't worry, they won't hear anything so feel free to scream."

Because she learned about happiness, she felt lonely for the first time. And because she knew unhappiness, she understood happiness for the first time.

Meanwhile, outside of the room, Ector and his wife were sitting by the door, being present as they were worried about Kay, thinking of looking after him. But they refrained from entering when they heard their discussion from behind the door.

"It seems like the Great Magus will become our daughter-in-law, dear."

"I just hope that nothing bad will happen from their union… like the country being destroyed."

"You worry too much, have some faith in our son."

"Ah~~!"

As they whispered, they widened their eyes in shock when they heard Merlin moan loudly from behind the door and continued to do so, making Ector let out a sigh as his wife laughed.

"She said she would make Kay scream, but it looks like the opposite has happened."

"I just hope Artoria doesn't wake up because of this."