Disclaimer: I don't own Inuyasha or My Hero Academia.
Jaken was really hard to time... his age is so random because he has done a lot of random exaggerations of time before.
I timed him around 150 when Inuyasha was sealed.
It was randomly noted that Yokai do die from old age, so I had to fill some holes around somewhere. Hope I filled them well enough.
Jaken was an imp, although he was formerly the King of an imp tribe, it did not deny that he was one of the weakest yokai species.
And like weak yokai, his entire tribe had been slaughtered by stronger ones.
But he was happy it happened, because he got to meet his Lord. Lord Sesshomaru.
He will forever pay his respect and give his loyalty to the perfection that is his Lord and never allows disrespect towards him.
Though his Lord's reckless ways worry him endlessly.
—
His Lord did not care for much, and did not care about much.
Though Jaken was shown kindness occasionally, it was not actual kindness, it was simply beyond Sesshomaru's ability to do so. But the rare acts of things close to kindness, one of the first one which was saving him–though not on purpose–and then allowing him to follow him after giving him the Staff of Two Heads, had taken his loyalty forever.
His Lord was perfection from form to name, was it any wonder he was taken at first sight?
"Enough Jaken."
Though he does get reprimanded often enough when he becomes heated at someone showing disrespect toward Sesshomaru. There was no regrets at yelling at the others, but he does feel slightly apologetic at his Lord for rambling perhaps a bit too long while he was defending his honor.
And this time they were trying to gain allies to fight the Panther Yokai Tribe trying to attack Japan.
It was a bit too hard even for his Lord to take on a whole tribe of those guys.
Not that he did not have anything but full confidence in his Lord.
But why oh why must that stupid half be sealed at this point of time?!
Does he know how much he had disappointed his Lord?!
The next time he sees him, he was going to give that brat a good talking!
Assuming he ever makes it out alive–nope, bad thoughts. There's no way his Lord would let him die.
A clawed footsteps down on him.
"A-Un!"
The two-headed dragon yokai snorts.
—
His Lord started a new habit–did it occur enough to be called one?
Yes, compared to other nonexisting habits, this one was serious enough to be called a habit.
First, he and A-Un would be left somewhere near the forest Inuyasha was sealed in and his Lord would wander off.
He would spend his time just waiting for his Lord to return with A-Un, who unfortunately held no respect for the imp and would not heed his commands.
His Lord would usually return with no facial changes to his mood, but Jaken could sense that his mood had taken a worrying turn.
"Are you worried for the half Milord? Ah!" He was mercilessly stepped on, his Lord had violent ways of expressing himself when he hit the mark. But he and his big mouth never learn.
A-Un continues to snicker and follows after Sesshomaru as Jaken pulled himself up from the ground, hurriedly running after his Lord.
"Wait for me Lord Sesshomaru!" And like usual, his lord didn't even look back.
It was more habit for him to say that line now.
—
Some of the shakiest points of time would be when that half-spider yokai existed. His Lord was reckless as usual, but his recklessness were particularly not a good idea when this half was around.
His too passive responses to people trying to lure and trick him into traps had caused Jaken quite a bit of grief. If he had hair, he would have plucked them all by now.
Then there was that strange group of humans and fox yokai.
The girl was dressed rather distastefully, did she think she could lure his Lord with showing all that skin? His Lord was a yokai of high-class perfection, nothing a human could ever match up to!
That idiot monk too made him blow his top off, but that wind tunnel of his was quite dangerous. He would rather keep a nice distance, let the man decided to take a swing and go for his Lord too. He could keep his groping tendencies among the human women.
Speaking of groping tendencies, he felt both pity and annoyance at the yokai slayer. Pity at her being the constant target of the monk, but annoyance at her for being the most dangerous to him. He, was an imp yokai. Though stronger with a staff, he did not want to be near someone who did killing yokai as a profession, and nor should his Lord.
Not that his Lord would not have a problem killing her with one hand.
The fox brat though, was the one he hated the most out of the group. He had tried to be cordial as best as he could considering they were both yokai, but the other had to pick at his height! Amongst other things!
And A-Un being the damn dragon he was gave no crap about Jaken being played around by someone else.
Even Lord Sesshomaru wasn't around for him to cry to when that happened.
—
Yokai lived long, much longer compared to humans, but they also had life spans.
Not that the life span mattered when most died by other causes.
But they still have life spans. The weaker the yokai, the shorter they lived. For Jaken, an imp, three to four centuries was about his normal life span considering his aging rate. He had been with his lord for about that long now, he could feel his own body gradually weakening.
But his Lord was as perfect as ever. He would be sad to see the day he wouldn't be able to keep serving him anymore, but he would do his best until then.
Furthermore, his Lord was still waiting for that half to unseal from the tree. He didn't want to go yet until he at least yelled at the half for making his Lord wait for so long. Though from the recent change of scent on Lord Sesshomaru's body, the half wasn't really a half anymore.
But he would forever be that bratty, loud, unrefined half to him.
Blood does not determine everything.
But sometimes it does and he hates himself for being an imp, one of the yokai without a lifespan to match his Lord.
"Snort."
"Yeah yeah A-Un, lucky you. You've been with Lord Sesshomaru so much longer before me and will keep being with him after me. I'm so jealous!" Jaken sighed and continued to wait for Sesshomaru to be back.
—
Sesshomaru had become kinder, and less violent. Though he was still occasionally stepped on and kicked when he says a bit too much and embarrassed the other.
Did he become kinder with time, or because of waiting and time?
But in any case, Jaken was dumped into a spring with no prior warning when he was nearing his lifespan and suddenly turned youthful.
He couldn't quite understand what happened at first and Sesshomaru said nothing, but turning around and leaving when he saw it having the intended effect on the imp.
Jaken's eyes watered. "Lord Sesshomaru!"
"Let's keep going, Jaken."
"Yes, I will forever be your loyal servant!"
And they would go back to the spring again and drag it back with them to where Inuyasha lied.
Sesshomaru wasn't bothered to find another servant like Jaken, and Jaken did not want it any other way.
"A-Un, we'll be staying together even longer."
The dragon yokai rolled both their eyes and snorted, as if to say, "Looks like I have no choice."
And they continued their journey and waiting.
—
As much disdain Jaken had for humans, he begrudgingly accepted their ability and intelligence with time. Though short lifespans they lived, they progressed so much faster than any long living yokai.
But he still hated them, for one other reason.
Identities! Papers! Technology with photo taking abilities, all the other crap that makes life so much harder!
"Jaken." Sesshomaru silently sipped his tea as he pushed all the work onto Jaken.
"Yes Milord, I will have everything done!" So he went to hire some fox yokai, and great, the one he had to find was the Shippo brat from before.
But things must be done…
"This is for Lord Sesshomaru!"
He bit his teeth and hired him. That year, the fox brat had three tails while he, grew one too many wrinkles from worry.
"Snort."
"It's so nice to be you A-Un." Jaken fell in a tired heap with paperwork around him.
The dragon yokai thankfully did not try eating any of it and left to go play with the nekomata that used to be the yokai slayers.
"But it's nice to still live to see all of this." He just wished there was less paperwork, how he wished he could use his staff to burn it.
—
His Lord had been very obviously happy–to him– sometime after the quirk era started.
It happened with a visit to the forest of Inuyasha, so it must be something to do with him.
Jaken, the loyal and great servant he was quickly started to set things up for the possible arrival of the half. Anything that could make his Lord happy could only be the unsealing of the half.
And behold, though it took longer than he would have thought so he had to constantly prepare and reprepare things, but the half was unsealed.
"Come, I will have Jaken draw you a bath. It's been a very long time Inuyasha."
It was his cue to do things, but—
"Eh, that old imp is still around? You never bring him around to see me so I thought he finally ended up dead somewhere."
—Jaken immediately took the bait.
"How rude, I am perfectly well and alive!" the nerve of that half, though yes, he should be dead with his lifespan, but Lord Sesshomaru in all his perfection—
"Jaken."
"Yes Lord Sesshomaru!" Jaken straightens up.
"Bath."
"Yes, of course!" he zoomed off, holding back from another round of words when he heard Inuyasha before he disappeared around the corner.
"Tch, still the same sucker."
He will give that half all the words he had been saving up for centuries after this.
He still had to call the fox brat back for more paperwork. Technology these days were even worse to deal with, though he also did not need to hide himself anymore in this strange world full of quirks.
At least he had underlings to deal with some of the more annoying work now, it was great to be a boss again (though his loyalty will forever be with Sesshomaru).
He still got a good number of centuries left in him before someone could take his spot as Sesshomaru's number one servant!
For those who don't get why the title is set that way, it's because Jaken's name means "Evil Point of View". o3o