as many souls as there be stars

Later on his phone starts ringing and he looks at it, then just puts it on the table where it vibrates with persistent calls for over 20 minutes.

"Don't you want to get that?"

"It's just Dean"

"Couldn't you just tell him you don't want him to call you so often??"

"I like when he calls"

"Then why not answer???"

"I don't have anything to say to him right now"

"Don't you think he might have something to say to YOU?"

Even more laterer, at the end of the night, bar closing, having seen Cas slug back an entire vodka bottle, "Hey you shouldn't drive, do you want me to give you a ride?"

"Oh, no thank you. Dean will drive me."

Cas pulls out his phone and they're like there's no way. It's 2am and Cas just ghosted him for 45 minutes. There's no-

"Dean," he'd answered on the first ring, "I'm 'too drunk to drive' can you come get me?"

It's Dean. He says, very cheerfully, "hey, this is Cas’s phone, who's calling?" like he's his secretary. Cas can be heard in the background talking about 'research' and 'swords'.

Dialogue establishes that Cazador has been successfully passing himself off as a regular noble for centuries, and Astarion confirms that while he's considered a bit reclusive, he does mingle with the upper class of Baldur's Gate and has a property specifically for hosting fancy events.

Vampires are camouflage predators, whose primary hunting strategy is to blend in with their prey until the perfect time to strike. Their ecological niche is not a particularly safe or stable one - they live hidden in plain sight, usually in sizeable cities, for easy access to prey, but they know that if they are discovered they will be rooted out and killed or driven away. They are rarely able to get away with attacking in public, where city guards might rush to the aid of a screaming victim - they have to isolate their target before killing it. The ability to blend in, to be overlooked by their target, until it is too late is essential.

Cazador is, as far as we know, the only true vampire in Baldur's Gate

This is because true vampires are aggressively territorial. Like most apex predators, they eat a lot, and need substantial territories to support them - even moreso if they have a partner or spawns. Ascendant!Astarion would need to hold onto the entire city, as Cazador did, to be able to feed himself and Tav without raising suspicion.

True vampires are relatively rare, but there are more of them than there are cities, so it's not uncommon for one to set up in an occupied city and try to oust the sitting resident. The challenger usually believes himself to be as strong or stronger than the current tenant: these territorial disputes usually end in at least one death, so they're not to be entered into lightly.

Astarion is very obviously a vampire: his fangs are visible, as are his bite scars; he's so pale multiple people comment on it; his eyes are red, etc.

Astarion is not a healthy vampire.

This is a man who has been kept on the knife's edge of starvation and tortured regularly for 200 years, and to another vampire, that would be clear from the state of him: Astarion is a camouflage predator who is so malnourished he is no longer able to blend in.

Tav will get an up-close look at his transformation over the course of the game and during the years afterwards: the more healthy and well-fed Astarion becomes, as his body catches up on its immense energy deficit and begins to recover, the better he will be able to mimic a living elf. His skin will be able to bleed, or blush, or bruise, none of which he's capable of while actively starving. Hia fangs will retract until he needs them, not invisible but less obvious - having them out all the time is a response to severe deprivation; he's so hungry his body can't risk losing prey to the split second it takes Cazador to snatch a rat back, so he's permanently in bite mode, hyperaware, ready to strike. Some body functions will come online that he didn't even know he had, the ones that are supposed to help him blend in - his eyes will start producing pigment to look darker, less scarlet and more burgundy, to be more easily mistaken for brown; his lungs will make him breathe automatically even though he doesn't need it, he'll start being able to eat normal food without getting sick again, though he still won't get any nourishment from it; he'll heal faster. He'll even be able to get drunk, though he'll burn through it very quickly. As it stands, all those extra systems have been shut down by his starving body - they're useful, but nonessential, and he needs every single bit of energy funnelled into just keeping him alive and functional.

There is probably an intentional bit of psychological warfare against the spawns on Cazador's part here - him starving them strips them of their natural defences, and every time he makes them leave the mansion to hunt, they have to do so knowing that they're poorly hidden and vulnerable. But it's established that true vampires treating their spawn poorly or outright abusing them is A Thing, so it's not the only reason - he sees them as property rather than people, he keeps them weak so they won't plot against him, he's acting out his own trauma from Vellioth on them, he just wants to - but it does feed into it.

Astarion can, at one point, identify old blood as belonging to the player character. He also gets excited at another point if an enemy character runs away, stating, "Now it's a hunt."

He says that "even stale, [he'd] recognise that bouquet anywhere." This confirms a few things for us:

He has a vastly superior sense of smell capable of identifying individuals by scent and - since he can tell who the blood belongs to even after some time has passed - following scent trails.

This confirms that although city-dwelling vampires may primarily hunt via luring a victim to a secondary location before killing it, they still have the "stalk down and chase" predator instinct. Since Astarion can't lure wildlife anywhere, this is almost certainly how he's been hunting to supplement his diet when he's not using the player as his personal caprisun.

The fact that he can scent out prey before killing it means he has this ability all the time - he can smell blood while it's still safely inside the owner's body.

So scent is probably relevant to how vampires process the world. The more time each companion spends with him, the more he gets used to their scent, starts associating it more with safety and camaraderie than with a potential meal, and so he becomes more relaxed around them. As he learns to link the player's scent with love and comfort and trust, the more likely he is to retreat to their tent over his own when he's injured or afraid or having a trauma moment. When he's fond of someone, something of theirs will go conveniently missing - he's moving their scent into his little safe space, it's comforting for him. He can tell when his lover is hurt or aroused or frightened - though not which of the three applies - from a distance, because his sense of smell can pick up the spike of adrenaline rushing into their bloodstream.

fall in love again and again...

so because Vampires Are Queer Now, writers are either morally against making that conflation with sexual violence, or are afraid of being read in bad faith if they do anything else with the idea. which turns both vampires as symbols and the conversation around them into sludge.

anyway