Disclaimer: I don't own Vampire Knight or any of its characters or plot. I only own my OCs and the plot that differs from canon.
To my guest reviewer from March 16: Oh yes, Kaname is a manipulator... I'm glad you like my depiction of him. I hope I can keep everyone in character. His motives and plans for Koharu will be revealed in time though they will change a little as he gets to know her. Can't say more than that~.
To Dei: I'm happy to hear that you like Koharu so far. You'll see more of her personality and what she has in mind for the VK plot in time :D.
To belladu57:Thank you!
To my guest reviewer 1 from March 28: I'm glad that you liked the chapter!
To my guest reviewer 2 from March 28: Hehe. I'm not 100% sure about the pairing yet though I have one in mind already. To be honest, I'm heavily leaning towards not pairing her up with Kaname because I feel like there are enough Kaname/OC stories out there already and I think Koharu and Kaname don't quite fit each other. You'll probably see in time why I think so.
A/N: Thank you so much for the many follows, favourites, reviews and reads, my dear readers! It makes me really happy to see that people enjoy what I've written :D I'll try to update this story once or twice per month, but I make no promises. I'm sorry that the updates will be rather slow, but I'm going to be a little busy in the coming months. I already have a plot and ending planned out for this story though and "just" have to write it down. Lol. So, it depends on whether I have the time or muse for it. Also, I should probably apologise for any grammatical errors, spelling mistakes, typos, punctuation errors and strange wordings that might occur in this fic because English is not my native language.
Anyway, I hope you like the fluff in this chapter and how Kaname, Takuma and Koharu get to know each other!
Last edited on 15.03.2022
Chapter Three – Settling In
Koharu was woken up by a knock on her door at half past five, shortly before sundown. For a moment she didn't know where she was until she remembered that she was at the Ichijō manor. She got out of the bed, stretched and received the maid.
She usually got up at 4 p.m. so she could enjoy at least one last hour of daylight – even as a vampire she couldn't quite part with the light of day. In addition, she liked to get up early because she loved the tranquillity of the morning; the time when no one else was around or awake yet.
The brown-haired Level C vampire she let in introduced herself as Honda Sachiko and was supposed to be her new personal maid from now on. She and four other maids brought Koharu kimono, underwear, some hair accessories and jewellery but also certain garments that surprised her.
The pieces of clothes in question were dresses, jackets and shoes. They had procured her western clothes.
'It's been a while that I've worn some,' Koharu thought, hit by a wave of nostalgia.
To be precise, she had never worn western clothes as Koharu. While she had come to love kimono and yukata, she didn't hesitate to take a dusky pink haute couture dress with her to the adjoined bathroom. The maids were about to follow her into the room, having been instructed to assist Koharu with getting ready, but she sent them away. Even if she was something like a princess in the eyes of vampire society, she wanted her privacy in the bathroom, thank you very much.
The marble and wood bathroom was as luxuriant as her new room even though they were smaller than her quarters in the Hiō compound. Not that the rooms were actually small if you compared them to normal, reasonable sized rooms. She wouldn't complain, though. Everything she needed to get ready she found inside the cabinets or the room itself.
After stepping out of the bathroom, Honda-san knelt down on one leg in front of Koharu, so she could absorb some of the maid's life energy via skin contact. Koharu had gotten used to this strange craving she felt whenever she needed life energy but kissing a stranger on the cheek to get what her body needed made her feel uncomfortable.
Nowadays the amount of life energy she had to consume to satisfy the craving was quite a lot compared to a year ago, and sometimes Koharu wasn't really satisfied by it for long anymore. The scent of blood was also becoming more and more enticing to her. She always got a whiff of it at the Hiō compound when Shizuka drank the blood of the humans that the servants brought her.
Koharu knew that she would get her fangs and that her thirst for blood and her vampire instincts would awaken one day. It was part of being a vampire after all. But she already dreaded that day and hoped it would come later rather than sooner. She really didn't want to have to deal with those issues.
Honda-san led her through the corridors and into the dining room, that smelt of human blood. Koharu cursed inside her mind. She'd hoped that the blood tablets had already been invented since she remembered the Night Class students complaining about their taste in the series, but it seemed like that wasn't the case.
Kaname and Takuma were already sitting at a sizeable table with a small variety of foods and drinks spread out on it. There were also two glasses filled with blood on the table– one for Kaname and Takuma each.
This would make things harder for her in the future.
She was informed that Ichiō was away on business – possibly to break the news that she was staying at his place to the other Senators – which she didn't really mind. They would have found out about that anyway. Koharu counted this as a small blessing and was glad that she didn't have to face the vampire elder at breakfast when she already had to stomach the fact that she'd have to regularly drink human blood soon.
"Good morning, Koharu-sama! That western dress really suits you," Takuma greeted her cheerfully, and she reciprocated it with less exuberance but the same positive attitude.
"Good morning Ichijō-kun and thank you for the compliment. Good morning to you as well, Kaname-onii-sama."
Kaname appeared to be a bit sleepy still. "...Good morning."
Then the realisation that Kaname and Takuma must have waited for her to begin with breakfast hit Koharu, and she immediately felt awkward and apologetic for being late.
"I... have to apologize. I didn't expect that I would have breakfast in company for once. I hope I didn't make you wait for too long?"
Koharu hadn't eaten a meal with anyone since she was human. Her caretakers had just brought her her meals back at the Hiō compound.
Takuma gave her a sympathetic look. She didn't know how to feel about it, but she guessed that it was well-meant.
"It's fine. We didn't have to wait for long, right, Kaname? Let's have breakfast before the food gets cold!"
During breakfast Takuma held a light-hearted conversation with Koharu that distracted her from the blood issue and Kaname chimed in whenever he felt like talking too. The Aristocrat asked her about her favourite foods, which then led to a small discussion about western and traditional foods. Once more Takuma's presence and his upbeat character made her feel welcome.
'He's adorable. I've known him for less than a day, but he's already well on the way to becoming my new favourite person,' Koharu thought. 'Takuma has some serious charisma.'
After breakfast their lessons began. They included mathematics like algebra, geometry and calculus, micro and macro economics, sciences like physics and biochemistry, literature and art, music, history, politics, etiquette and dancing, and languages.
She noted that the level was a lot higher than what humans who appeared to be the same physical age as the three of them would learn and about university level. Vampire children grew up slower than humans but they possessed superior intelligence.
Koharu had noticed that she grasped concepts faster than in her past life, where she had to study hard to get good grades and even then failed at times. As a vampire she even remembered information better. It was unfair.
'I would ace that horrid chemistry test from my final year at school if I tried it again now', she thought to herself.
It made sense in her opinion, though. Vampires needed blood, primarily human or vampire blood, to live, so they had to be able to get it somehow. Naturally, as the predators they were born to be, they had to not only be stronger and faster than their potential prey but also more sharp-witted. From their appearance to their mental and physical abilities vampires were born to be apex predators. If they wanted to be, of course.
Throughout the lessons Koharu stayed with Kaname and Takuma. Koharu was glad that she didn't have too much trouble with keeping up with the subjects that were discussed or brought up in their lessons. She'd been confined to her cage for more than two decades and thus she had more time than ever to extend her knowledge in almost any subject she desired.
However, there were certain topics she hadn't been taught about or hadn't been allowed to learn about – the current conflicts of the world and politics for example. So she would be 'protected from outside influences', as her caretakers used to say.
There had been no need for a dance teacher or dance lessons either, because Koharu wasn't supposed to attend a soiree. Ever.
As a result, when it was time for the dance lessons, Koharu stood there like a fish out of water. The female teacher looked at her with high expectations as Kaname held out his hand for Koharu.
After a moment of hesitation Koharu placed her hand in her cousin's without comment as she internally panicked. She had never been good at admitting her faults or that she was unable to do something. Especially in front of Kaname or people with certain expectations of her.
With her poker face on, she let Kaname guide her steps. And promptly stepped on his foot, for which she quietly apologized, her distress growing. Kaname looked down at her but continued dancing with her. It didn't take long until it happened a second, third, and even fourth time.
"You weren't taught how to dance, were you?" Kaname observed.
She nodded sullenly in defeat, unable to deny it. She hadn't danced in her past life either and hadn't been particularly athletic though she'd liked to swim and made sure to stay healthy by going on walks and watching her diet.
Takuma, who had been dancing with a smitten maid, had kept an eye on the other pair out of interest and piped up, "That's why you looked like a little fawn that is still shaky on its legs."
The smile the teen sported was free of any maliciousness but his comment managed to make Koharu feel more ashamed about her non-apparent dancing skills and irked her at the same time. She blushed involuntarily, which seemed to amuse both Kaname and Takuma.
"What the young master means to say, Koharu-sama, is that you are already doing admirably for someone that hasn't danced before," the dance teacher tried to appease her.
"She was certainly talented in regards to stepping on all of my toes at once," the Kuran ancestor commented in a dry tone.
Koharu had no idea what to say or how to react to that, not having expected that Kaname would try to tease her of all things. She wasn't used to receiving criticism or getting teased anymore after over twenty years of receiving nothing but praise since she'd been born as a Pureblood.
'I've become arrogant and boring,' she thought to herself. 'I should work on that.'
"...I just followed your lead, Onii-sama," she retorted innocently and looked up at the taller teen, who still had an arm around her waist.
"Maybe you wanted to get stepped on your toes then, Kaname," Takuma commented airily.
Slight humour was displayed on Kaname's face. "Perhaps I did."
'Oh my... I hope I haven't accidentally triggered Kaname's masochistic side.' Even if that was the case, Koharu couldn't help but hide a smile behind her hand.
They were released from their lessons at half past one in the morning. Koharu stared out of the window and at the entrance of the forest, burning to take a walk and get another taste of freedom.
"Koharu-sama, would you like to take a walk in the forest? I could show you around." The blond Level B had easily seen through her.
She readily jumped at the chance. "I would like that, yes."
"Great! Kaname, do you want to accompany us?" Takuma asked his friend.
Kaname closed his eyes in contemplation. "A walk certainly wouldn't hurt."
Once the three vampires had put on jackets and decent shoes for outside, they entered the forest that surrounded the Ichijō estate, guards following them at a distance. The air was cool and slightly moist at the end of September, but it wasn't like vampires could catch a cold.
Koharu relished the wind on her face and in her hair, the earthy, musty and woody scents that she detected in the air, as well as the smells of smaller nocturnal animals, that all ran away once they got too close, sensing that something dangerous was coming their way. Animals didn't like vampires.
Koharu could even feel the plants to a point; the trees more strongly than the rest. Her heart grew lighter with every step further into nature. She was intrigued by everything she perceived with her superhuman senses.
'It's so different from what I could discern as a human.' She was awed.
As she followed Takuma and Kaname on a trail, Koharu spotted a cherry tree amidst the pine and spruce trees. The traditional Japanese garden she had a view of from her windows in her quarters back at the Hiō compound had a few sakura trees too. They'd bloom during nearly all seasons because of Shizuka and perhaps even Koharu's influence.
Even now she could feel her power, magic, whatever it exactly was, reaching for the tree's life force. Koharu wanted to know if she could make the cherry flowers bloom just like Shizuka, so she stepped closer to the tree and placed one hand on its bark. The other Pureblood and the young Ichijō heir stopped their chat and watched her in silence.
The bark felt rough under her palm, but she relished the touch, as well as the foreign feeling of another life force she sensed underneath it. The tree was alive and seemed to be aware of her on some level. Its presence was oddly calming.
Just a touch, more like a soft caress, with her power was enough to strengthen the tree to eagerly follow her request. Leaves began to sprout in a matter of seconds, then the buds appeared and opened up to reveal beautiful, soft pink cherry blossoms. Koharu was happy that it had worked.
This new awareness of trees and plants was fascinating but also strange to the former human woman. She'd known that the ability to manipulate plants was rather common in the Hiō Clan, although not everyone possessed it, and was thrilled that she had it.
'I need to practise this ability... Maybe I should try to plant some flowers sometime?'
Having supernatural abilities was one of the few highlights in her life as Pureblood.
"Ooh! You made the cherry blossoms bloom!" Takuma was excited to see her powers in person.
Koharu almost jumped at Takuma's voice, not because he was loud but because she'd almost forgotten that he and Kaname were there too. She'd been too focused on the tree. Judging from his look, Kaname was gauging her ability in silence.
She smiled at the blond in contentment, uncaring about Kaname and their guards at this moment. Somehow, Koharu had the feeling that she would become a tree hugger after this experience, more than she already was.
"Why don't we have a picnic here tomorrow after our lessons?" Takuma suggested. "It's not everyday that we can enjoy a sakura tree in full bloom in autumn. It's right around Tsukimi too."
She'd learned that Tsukimi was a traditional celebration of the autumn moon, that included gathering at a place where the moon, that was brighter at the time of the harvest, could be seen.
Kaname gave Koharu a knowing look. "I have the feeling that this won't be the last time that we see a cherry tree bloom out of season, but I agree. I would like to have some of your personally prepared tea, Ichijō."
"I like the idea too," Koharu gave her consent, already looking forward to the picknick.
It had been a while since she had anything to look forward to.
"Then it's decided!" Takuma seemed happy that his proposal had been accepted and that his skills were valued by Kaname.
He and the Kuran ancestor showed Koharu more of the area before they returned to the manor.
Since Tsukimi had been a traditional Japanese celebration in the past, Koharu wore a fitting kimono to the picnic. Even Kaname and Takuma put on traditional clothes.
It was a perfect night for Tsukimi – the moon shone brightly, there were barely any clouds in the sky, and it was dry although it was a little cool. The cherry tree, underneath which the servants had prepared a blanket, pillows, food, and everything that was needed for a tea ceremony, still stood in full bloom and smelt pleasantly.
Koharu was observing Takuma as he performed the tea ceremony for her, sitting opposite of her. She'd learned how to do it as well, but she rarely had the chance to perform it for someone; the last person who had received her tea had been Yusuke-san, Shizuka's lover.
Each of Takuma's movements were refined and elegant. He knew what he was doing and the teen looked like he was enjoying it. Also, he had remembered that matcha was Koharu's favourite kind, which delighted her.
She received her tea cup first out of chivalry and took a few tentative sips from it. "It's delicious. You are very good at this, Ichijō-kun," Koharu gave Takuma a small, satisfied smile as she spoke her opinion.
The teen had clearly been waiting for her assessment. Kaname drank from his tea cup in silent agreement.
Takuma blushed lightly at the praise and beamed at her. "I'm glad you like it, Koharu-sama!"
"You can drop the honorific if you want," she proposed, wishing to be addressed by him like Kaname – in a more familiar and less distant way.
She wanted to make some more friends now that she had the opportunity to and Takuma was very likeable. Even if she had some prior knowledge of him and his personality, she was usually pretty good at assessing someone's character as well. Anyone would be happy to have him as a friend, and it was odd if she was the only one who was addressed with -sama.
The teen blinked in surprise before he smiled at her again, appearing to be in a jovial mood. "Alright... Koharu-chan, but then you have to call me by my first name, too."
She didn't mind that at all. "Deal, Takuma-kun."
The three of them enjoyed their tea underneath the moonlight and cherry tree. They ate Tsukimi dango and other snacks the servants had prepared for them as they chatted about various topics. Koharu had the feeling that her life was finally changing for the better.
'It has only taken over twenty-six years,' she thought as she gazed up at the moon before she looked back at Takuma who was drinking from his tea cup.
'I wonder how he can drink his tea with jam, though. That's really weird.'
As the days passed, she got to know the people living at the Ichijō estate, including Ichiō, who joined them at breakfast, lunch, or dinner when he had time and was at the manor. Koharu was careful what she said around him, or anyone who wasn't Kaname or Takuma for that matter.
Kaname hadn't lied when he said that this place could be considered worse than her cage – her every step was being watched. Koharu felt that she might develop some sort of paranoia after living here for a while but thought that it was a small sacrifice to make in exchange for some more freedom of movement and the opportunity to make friends.
She took a neutral stance whenever they discussed matters like the Vampire Council or vampire politics, balancing on the line in between pro or contra Senate as to not earn the ire of either Kaname or the vampire elder.
In secret though, she was of Kaname's opinion. The Senate was corrupt and needed to be abolished. However, it would need to be done carefully and with a fitting replacement already prepared, so there wouldn't be a power vacuum like in the manga series. Too many humans had been attacked or killed by vampires that had gone out of control after Kaname's rash disposal of the Senate – the only thing that had kept them in place before.
Ichiō was of the opinion that she should be introduced to vampire society soon and Kaname shared that view surprisingly enough. Koharu wasn't very eager about getting involved in political schemes and gossip but was aware that she'd have to bite the bullet sooner or later. She didn't want to think about all the small talk, pretending and scheming that laid ahead of her; the mere thought made her shudder in repulsion and made her question if she could really do it.
'It's going to be a lot of work. But it's necessary,' Koharu concluded.
She'd found a purpose after leaving her cage.
Now that she was staying with Kaname and would remain at his side for an uncertain amount of time, she had to make preparations for the possible future. She wouldn't just let things happen like in canon if she had any say in it. She'd already interfered in it by being born and by writing that letter for Shizuka.
This was her life and Koharu wouldn't watch a tragic story she already knew unfold before her eyes.
The reborn woman wordlessly stared at the girl standing in front of her while the girl was doing the same after having greeted her appropriately.
'So this is Seiren, huh?'
Since their lessons had just ended, Koharu was in the drawing room with Kaname and Takuma. Seiren had suddenly entered the room to report her progress with her weapon training to Kaname. Koharu didn't mind that she had interrupted the game of chess that she was losing against Kaname. Again.
'For someone that plays chess so well he could have done a better job with his scheming in the series,' she thought, feeling a little petty because she was losing again.
The girl was about three years younger than Koharu's perceived age of thirteen or fourteen but a lot younger in reality. This wasn't just because of Koharu's twenty-two years of human past life but also because Seiren had grown up normally as a human and would continue to do so until adulthood even though she had been turned into a vampire by Kaname.
People who were born as vampires, however, grew up a little slower in body than human children. This meant that Seiren would grow up faster than Koharu or even Kaname and Takuma.
At the moment, Seiren was still training to become Kaname's bodyguard and was far from the competent servant Koharu remembered her to be. But she already had a stoic, serious attitude.
Talking to the girl proved to be difficult; she was a quiet person, as much as Koharu, so most of the conversation after introductions were over was being held through evaluating looks and prompted by Takuma's conversation starters.
In the end, Koharu decided that she liked the girl and her no-nonsense attitude although she had to admit that it was frustrating to chat with someone who was as quiet or even more quiet than her. She wondered when she would meet the other people from the future Night Class.
Koharu spent a lot of her time with Takuma and Kaname even after their lessons, though they sometimes were away from the manor or otherwise occupied too. Kaname was often invited to attend soirees or balls, even some Vampire Council meetings. Sometimes Takuma accompanied him to the latter. Also, Takuma received private sword lessons from his grandfather whenever Ichiō had the time.
She felt left out at times but knew that it was just a matter of time until she could join them. And she'd already been patient for a long time, so this should be nothing.
Koharu passed the time she was left alone by reading books, drawing, taking a walk outside, playing the flute, or practising how to create a familiar and trying to see through its eyes. It was easier said than done and required a lot of concentration.
When Koharu saw through the eyes of her familiar, she forgot about the world around her. This wasn't a problem when she was alone and wasn't being watched, but she wouldn't be able to use this ability around other people without them noticing that she was mentally absent.
She needed to be able to do this though because she wanted to use her familiar to spy on Ichiō and the Vampire Council.
The topic of their favourite book genre came up one time when Takuma was playing a game of hanafuda with Koharu while Kaname was absorbed in a book on a nearby sofa. She'd asked Kaname what book he was reading.
It turned out to be a classic about two friends growing up and living in war times. One of them became a warrior who joined the war out of a sense of duty and the wish to protect his friend while the other one became a merchant and had to face other issues. The warrior died at the end of the war and story but kept his promise to return although it was as a ghost and just for one last meeting. He vanished at the end of the conversation with his friend, leaving only chrysanthemum flowers behind.
Koharu had read the story in her literature lessons at the Hiō compound. "I don't like tragedies. They make me sad," she said, turning over another card. "I prefer stories with a happy ending."
Kaname looked up from his book. "Sometimes tragedies can't be avoided."
She wondered if Kaname was speaking about his own experiences. "That is true..." Her eyes shone in understanding as she thought of Yusuke-san and how she'd died as a human. "But that doesn't mean that one shouldn't at least try to prevent them with all their power."
"I wouldn't have pegged you for such an optimist," Kaname retorted wryly.
She wondered if her mindset could truly be considered optimistic. The reborn woman just disliked emotional or physical suffering. Koharu had had enough of that.
"Well, I wholeheartedly agree with Koharu-chan," Takuma commented. "I can't stand tragedies either. What kind of genre do you like then, Koharu-chan?"
"Comedy and..." she could feel herself blushing, "...romance." The romantic in her had never died and it couldn't be sappy enough for her.
She'd always been a dreamer.
"How childish." Kaname sported a faintly amused expression with slightly upturned lips but didn't appear very surprised.
She blushed harder at his commentary. "And you have the same taste as an old, bitter man. Not everyone can be fond of dreary and depressing stories."
She was aware that Kaname was actually something like her great-great-grandfather and couldn't resist that snide remark. Kaname wouldn't know that she was aware of his true identity just through this, she guessed.
"So I have the same interests as an old, bitter man?" Kaname repeated dryly, slightly irked if Koharu interpreted his expression right.
"Sometimes you do seem rather old-fashioned, Kaname," Takuma added his opinion good-naturedly, which earned him a frown from said old-fashioned person.
'Oh my, Takuma. Despite your friendly nature, you can be savage.' A small laugh escaped from Koharu's lips. 'Ah, I wonder how long it's been that I've laughed? Wow, that thought is kind of depressing.'
While the other Pureblood was watching her, the Aristocrat smiled back at her as if she had just gifted him the most precious present.
"As for me, I prefer mystery novels, but I don't mind some romance and comedy either," Takuma returned to the topic they had been discussing before. "You know, I have a series that you might like, Koharu-chan... Have you ever read manga before?"
"My caretakers thought manga were inappropriate reading material for me and that they had no educational value." She avoided a direct answer.
"How right they were," Kaname commented.
Koharu had actually been a huge manga and anime fan in her past life but hadn't been allowed anywhere near them in her new incarnation. For years she'd suffered from serious manga, anime and internet withdrawal. She wondered what kind of manga there were in this world.
"Eh?! No way!" Takuma was scandalised by either Koharu or Kaname's remark, or both. "Manga are an important cultural heritage, and you can learn a lot about human culture and the like by reading them!" he protested before he turned to Koharu again.
"If you want, I could show you my collection."
A. Collection. Of. Manga.
She had no idea how she could forget the teeny-weeny detail that Takuma was an avid manga reader in the Vampire Knight series. This seemed to be true for his real life version as well.
Koharu jumped at the offer with sparkling eyes. "I would love that, Takuma-kun."
"Alright! I'm going to introduce you to all of my favourites!" The Aristocrat was as excited as her.
The two of them didn't bother to bring the game of koi-koi to an end as they stood up.
"Are you sure you don't want to come with us, Kaname?" the blond turned to his friend at the doorstep. "You've never seen my manga collection before."
"No, thank you, Ichijō. I'm quite content with my dreary novel. Enjoy yourselves, children." It seemed that Kaname didn't share their passion.
He just didn't know what was good.
'Reading those gloomy tragedies has to have a negative impact on Kaname's mood and psyche. I should try to do something about that...' Koharu mused. 'But first, manga here I come~.'
A/N: I hope you enjoyed the interactions of the characters! Can you guess which kind of animal Koharu's familiar is? :D
Concerning vampire age/aging: If you've read the manga, you've surely noticed that the vampires sometimes talk about 'vampire age' and 'human age', e.g. when Yuuki asks Takuma at his birthday party how old he turned now, Kaname's comment about human children and that they age fast, and how he seems to be at least eight years older looks-wise when Yuuki was a baby but later when she's around twelve he doesn't look older than sixteen or seventeen. There's also the issue of vampire pregnancies lasting about 2-5 years.
My explanation goes like this: vampire age is the age the vampires physically appear to be. A vampire child grows up about two times slower than a human child. So, in two years a vampire child only grows about one year - the vampire children grow up slower in body than the human children. Their minds, however, age just as fast as a human child's and they possess superior intelligence (the latter was stated in the manga). This would explain Hanabusa's intellect at a visibly very young age, as well as the advanced classes of the Night Class.
Vampire age= the age a vampire physically looks like
Human age= the true age according to the calendar
Example: Takuma appears to be 18 in the manga but is actually at least twice as old in reality, about 36-40 years in normal human age.
After a vampire has reached adulthood, they age slower, or, in the case of Purebloods not at all.
Level A Purebloods are technically immortal and do not age after reaching adulthood and may even alter their appearance to look like a child again (referring to Lord Toma and Kaname here). Level B Aristocrats live around 500-1000 years if it's true that Takuma was able to guard Kaname for a thousand years. They do age but not as fast as humans. Level C common vampires may live around 320-400 years (this is headcanon as it is never mentioned in the manga).
Level D ex-human vampires like Zero continue to grow up like a normal human until they reach adulthood. Then they age more slowly. If they don't get stabilized by drinking the blood of their creator, they turn into Level E. If the Level E are not killed, I estimate that they may be able to live about 160-200 years - twice as long as humans can. Is a Level D stabilized they become Level C, common vampires.
Once Yuuki was turned into a human, she aged like a normal human up until she was turned into a vampire again.
Also, I suspect that a vampire's, or perhaps even human's, lifespan can be extended by drinking the blood of a Pureblood (referring to Zero and the former Hunter Association President here).
In any case, this is the aging system that I'm going to use in this fic. These are just my own observations and what I've gathered by reading the Vampire Knight manga, wikia, Vampire Knight Memories and some discussions about this topic. I hope it makes sense :)