Ok so I've been thinking abt this 4 a while and I came to a conclusion that if there is a true united and connected (no matter how badly) vampire society then there must be norms? Some sort of rules or traditions. Now unfortunately Castlevania doesn't tell us much here, except tidbits such as having philosophy and a general sense of who is and who isn't in the community. So let's use logic instead. So usually, in the animal kingdom and human culture, norms and expectations, especially of beauty, were based on proving oneself to be succesful and therefore of the ability to afford luxuries that stand against reason of need. Take exotic birds for example; the show off of colors shocks and appeals to females (usually) but also makes it easier to be spotted as prey. The takeaway is ofcourse, that the beadzzled male can simply, by strength and intelligence, afford to be bedazzled. During human history, at least for most of, it was a signifier of wealth and class to be chubbier or even obese. The unspoken context was that even though most couldn't afford to feed their family, you were able to eat more than you needed or even wanted. Similar thing was for nails. Famously, in China, during the Warring States period (around 475-221 BC) long nails became a status symbol; a symbol of not doing labour, therefore not needing to have nails cut short for said labour. An added bonus was definately that healthy nails require a good diet, oils and frequent washing for good appearance; and can be decorated for extra measure.
Now back to the vampires. Considering the long nails of every vampire we see, and the knowledge that they can even be used in combat (see for:Raman) we can safely assume that linger nails are part of vampire signifiers and naturally occur afzer the transformation aling with fangs. Even characters who we would describe as practical (Dracula, he's dramatic but a scientist goddamit he knows what could be under) have them. I checked but unfortunately we don't see much of Tera's transformation but it'll definately be cool to find out if it makes it into her new design. Now we could assume that maybe nails are results of age but I feel as if that were the case again they wouldn't be that common.
How do vampires see their nails? Similar to humans, one would think, but i feel like there's more philosophy in there. Many vampires see their nails as as proof and extension if their animalistic side, cue trying to cut them and keep the human-short (great example is Lenore, who out of all vampires seems culturally very much still human or at least she tries to be) or embracing it and having literal claws (Dracula). But I want to talk about the detail of Carmila having red nails. With no knowledge of vampire technology I'm gonna say she used a formula way back from the Zhou dynasty in China at around 600BC or the Ming dynasty. Either way nail polishes of the time were limited in color but we knew they had red and adored it.
Why did I have this rant? Because I believe vampires use nails as virtue signaling.
Think about it. Vampires as a species are very cruel and deceitful so it's hard to know where somebody stays. But nails? Immediately u get the picture. Carmilla didn't just look good in red, she was the only general with colored nails, even Raman kept them natural (prob for combat but still). Think of the implications? She saw her vampirism as an extension and addition to her greatness. The color? Symbol of passion and prosperity. And upkeep? Probably expensive and rare, I mean she is a war general, I doubt that leaves time for manicure, but she did it anyways, probably HIRING HUMANS for it too. AND it matches her outfit. So u have these old vampires who keep their nails long as they accepted it, and think "yea this works" when all of a sudden a Bad BitchTM walks in and how do they know she means business? Colored nails.
And what does that leave the rest with. Think of all the times Styria hosted parties, galas and meetings with other vampire nations, putting up a good face, just for Lenore to cut her nails. Imagine the outrage and pity. She's the diplomat!! And yet, in company, she keeps her nails short. She already looks like a young girl, probably turned against her will, and the nails? Knowing Morana and Carmilla that had to be a constant fight. How could she represent them like this? Does she hate the gift of eternal life they've all been gifted with?
I imagine she tried to keep them long. For some time, probably an important politics season. Maybe she liked them, maybe she was waiting to cut them off, when she accidentaly cut herself. The pain. Anyone who has longer nails can tell u this is more often than u think, and considering vampire length and probable strength those cuts are good and deep. She cries. Of course the wound is already healed, ofcourse Morana and Carmilla yell how it'll pass but what they don't get is that the pain still happened. And it will again. And nobody understands.
She probably likes Hector's hands. He kept his nails short, he's a man of work, and thinks she likes the possibility of what he can do. But she just likes the nails. She even sometimes tells him to cut them shorter, since she wants to see how long and gradual human nail growth is. She enever tells him that, she lies and says "claws are for vampires" and she hates it. When she kills herself, Hector goes through the quartet's rooms for things and information and finds so many nail upkeep sets, hell even Striga has them. And Lenore has. Well a clipper. She never kept more. She couldn't.