In Act 1, the Astarion bite scene can be triggered after the player investigates a strange boar that is drained of its blood.
In the middle of a long rest, the player catches Astarion creeping up on him.
Realizing Astarion is a vampire, the player is then given a few choices:
Option 1: To support Astarion allowing him to feed on you (+5, +10 Approval)
Option 2: To reject his request. Astarion leaves, going into the forest looking for an animal to feed on. You'll still be able to romance him later on.
Option 3: To attack him. If the attack roll is successful you will kill Astarion with a sharp wooden stake. If it fails, Astarion will be injured and leave the party permanently.
Choosing to let Astarion feed on you will give you the Bloodless Effect: -1 to Attack Rolls, Saving Throws, and most Ability Checks. This effect can be removed with Long Rest, the Cleric spell Lesser Restoration, or the Paladin's Lay on Hands.
Allowing Astarion to feed on you will give him the Happy Status Effect granting him +1 to Attack Rolls, Saving Throws, and most Ability Checks. This effect is removed after a Long Rest.
