The Pale Elf - Act 3 quest *spoiler*

[Jet]

Why does not agreeing to help astarion conduct the ritual result in him remaining a vampire spawn? He still kills cazador you just dont agree to help him soo not sure why he cries and curses you. Anyone explain?

If you appeal to his better nature and convince him not to conduct the ritual from the beginning everything plays out the same. Soooo what does him being a spawn entail? Theres no master anymore. is there no way to remove that given caz is dead?

[Shale]

A Vampire Spawn is basically a weak vampire. They get all of the weaknesses with few of the cool powers (they still get some, like enahcned strength and regeneration, though the Tadpole removed these benefits along with the drawbacks for sake of game balance), and of course they're bound to their master's will.

A Spawn can become a True Vampire by drinking their master's blood (presumably while they're still "alive" for lack of a better term). Astarion either skips the True Vampire stage and jumps right to Ascendant with the ritual, or he's too emotional to even realise he could become a True Vampire and kills Cazador in the moment, losing the opportunity for him and the other Spawn.

I'm unsure if a Spawn need specifically their master's blood, or if any True Vampire's blood would do. If it does need to be their master's, then killing Cazador means that all his spawn are stuck that way, if not... Well most likely the same result, since no vampire is going to give their blood to another vampire's spawn. They don't have a master to order them around anymore, but they're still stuck as weak vampires.

[seeker1]

Hmmm, so a spawn is like the opposite of Blade. All the weaknesses, and few of the benefits....

Obviously, Astarion would normally be vulnerable to sunlight, it's just the tadpole took that away (as he found out). But then he also lost the regeneration.

https://roll20.net/compendium/dnd5e/Vampire%20Spawn#content

Also, note the "official" rules say they can only bite the incapacitated or grappled; I notice Larian modified that a bit. Also, he has no claws (of course those might be a massive giveaway, too).

From a lore perspective, I think if they become full vampires, they can act independently of their master; Cazador keeps them as spawn so they can't be.