I went throught the old
Lords of the Darkness module and here are some notable finds/connections;
more evidence for Astarion potentially being a greater vampire, or at least a lesser vampire, not a vampire spawn;
"A greater vampire had all the abilities of a lesser vampire and could also move about freely in daylight."
"During the hours of daylight, the greater vampire retained its superior strength and spell immunities, but could not use any of its special abilities such as life-drain, shape-shifting, or gaseous form."
Greater Vampire Abilities according to book:"These creatures possess all the regular attack forms and abilities of lesser vampires." Here is a notable one:
"As is well known, vampires may project a powerful charm through their eyes. The charm certainly may be used against those of the same sex and lasts indefinitely. As an alternate usage, when the monster desires to remain inconspicious, a creature making eye contact with the vampire is subject to a suggestion spell." -
suggestion spell according to 5e"In addition, their gaze weapon also may be employed as a hold person spell.
'"Another talent they may employ is to summon minor demons to serve them for up to 24 hours. This only may be attempted during the hours of darkness, obviously,..."
DMing the Greater Vampires:"Greater vampires are far more deadly than their lesser counterparts. In almost every case, the creature will adopt the persona of a normal citizen, frequently wealthy, and will do its utmost to keep its true nature a secret..."
- MC is being charmed by a lesser/greater vampire. Vampire spawn doesn't posses the ability to charm (according to 5e) - for reference
https://forgottenrealms.fandom.com/wiki/Vampire_spawn- Astarion is deliberately hiding facts about himself and giving you half truths; I feel like his persona is cracking, if you start looking at dialogue options where you question him/taunt him, sometimes tease him. He loses his posture when he gets a question, that he doesn't expect. I believe that's when MC is getting the most accurate info.
- Astarion mentions we will figure out his other quirks, if you talk to him after the feeding -
for reference. This makes me think he is already hiding something.
- There are some buggy scenes before he bites you, showing him sneaking off into the night. He might be practicing his (new) powers, not only hunting for snack.
- The summon demons made me chuckle a little, as it fits this hellish setting so well. Don't you think?
- The only weakness that we know of as, of right now, is the water, this might be something that is just not implemented during EA. If he starts being weak towards some other things that a vampire should, I think he potentially could have been greater vampire already before being abducted.
Maybe he still served Cazador, maybe Cazador wanted a vampire that could walk in the sunlight to do his dirty work. We only have Astarion's word that Cazador turned him. This might not be true.
What if Astarion was stuck in hell for a while instead? Maybe he boarded the nautiloid at some point in hopes to escape? Just like Karlach?
Cazador could have been the reason why he ended up in the hells and that's why he would want to kill him.
I also saw this comment on reddit some time ago, it could make sense, for this theory -
for reference.
I believe vampires can still be good, but like Drow and goblins, they've got a strong tendency for evil.
I don't think this means that he would betray you no matter what, it's just a theory about his backstory.@Nicottia;;
Thanks for your thoughts as always

It's always good to stay a bit grounded. That dialogue indeed might just some fluke, but it did made me question him.