// kind of a second part to this (curse) hc post...
To get to the gist of it, the Naberius birth process is not what one would say is a 'common' method. It isn't through conception and traditional sense at all, nor is it by anything like eggs, etc. It is solely through their magic abilities. Unfortunately, it takes a lot of mana, making the parent overall weaker due to permanently losing the amount that was used; because of this, it's not done often until dire. Also, due to the curse, it needs multiple attempts. It is extremely exhausting and gets worse with every try. (Yes they technically can have a child the "normal" way, but it makes "inferior" offspring, so they don't bother. There's also consequences to it.)
The Naberius do not do things like getting married or dating, nor do they find partners to pass on their blood or fall in love with; those are all distractions that hinder their duties—temptation will get corrected. If a new hound is needed, they are manifested, materialized into reality with their magic. Gender isn't an issue because they are pure mana formed by their hands and third eye within hours. However, because of the curse being the source of the mana in their blood, it ends up being passed down.
Not every born (manifested) offspring can handle the curse though, and multiple die within years before one can actually bear it. (For example, Kalego was the fourth attempt who finally survived.)
Why create another if they are technically immortal already?
If they don't create after some time, the curse will become more painful as millennia pass, threatening to kill its host in a brutal manner.
If a Naberius wanted to stop the entire cycle, they can't simply quit. The curse has a hold; it has a calling that they need to stick to these 'traditions', as they see them. The possession is controlling and alters their minds to stay loyal and strong to their duty as guard dogs, but the hellhounds themselves are unaware of this fact; everything they decide on just feels right.
The curse does all of this because it must be fed to keep manifesting—practically a parasite. The loss isn't only that alone, but also something that feeds it to make it more powerful. Whoever can't handle its possession is needed fodder, which might make the Naberius seem heartless, but something inside them tells them to keep trying, to keep repeating the pattern no matter what; that sacrifice is necessary. Some of them may be colder than others, some might not even care about the loss at all, but the one thing buried in their mind is that it's overall for the greater good of their bloodline.
Each time there's a success, the curse advances. The form of the Naberius have changed due to this. Originally only looking like large feral dogs, over time their experiences with interactions and what they've learned have allowed them to appear more human-like or at least be similar to their elites to be presentable. Being able to adapt to their surroundings, participate in more activities and communicate better is of importance. In their minds, they have to be able to conform to efficiently provide.
So what do the older Naberius do after serving their purpose? They continue to serve if needed anywhere, though if too weakened, they essentially retire—often back into hiding and living as ravenous beasts. Due to the curse, it can be challenging. The possession of it may linger and urge their minds to try harder—to keep working and make them feel like they're going mad or that they should cease their own existence. They can't even help create another Naberius because their mana can't produce enough magic for it anymore. Not only that, but the curse that lingers within their blood wants nothing to do with passing 'old magic' that won't advance it. Even if they were to attempt, the curse would instantly kill the offspring without feeding off of them.
Although Kalego (the youngest) is most advanced and can be somewhat aware, he is still possessed by his bloodline's curse. He has a little resistance from his growth, but his consciousness still displays a lot of the same mentality. He is still proud of everything his clan does, feels he never wants to quit his purpose as a guard dog and wants to keep his curse. However, the awareness he does possess makes him unsure and not really want to manifest another Naberius. It is because he can clearly remember the trauma he'd gone through growing up and how much pain he'd been in for many years as a child. Being 'softer' than the others of his clan, he simply doesn't want to have another suffer the same way he did, especially when so young. It still feels wrong for him to stray though...
Tragically, over time with his decision, he will have consequences. Although the curse can kill him or try to take hold of his consciousness more, it can also keep him living in agony for punishment if it wishes to do so. The curse is a lot more powerful than it had ever been, so it hadn't needed to feed in a long while. Kalego himself does not know of any sort of time limit and is oblivious to how the curse works as a whole. All that he knows is that it exists and there were sacrifices—one should be proud to earn their scars and third eye after an excruciating yet successful possession. It meant becoming a guard dog or worth, and to have the honor of protecting their 'treasure'.
(if it's still super confusing just think of it as a really fucked up tulpa fhskdfs)