I hope this helps.
Q: The variety of alignments in Baldur's Gate I & II allowed for many interesting party compositions and conflicts (for example, Edwin becomes openly hostile towards some companions and will straight up start a physical fight with them or refuse to be in the same group as them due to his Lawful Evil alignment). It's been said there won't be an alignment system on Baldur's Gate 3 as it's no longer relevant to 5e, but will we still get to have openly evil/selfish party members that actively support "evil" actions and might leave the group if you play in a more heroic fashion, or will all party members have a more neutral/good behavior?
Jan: Alignment may carry less weight in 5th edition, but all companions definitely have their own moral compass. Some are fine with evil and underhanded deeds, others are not - and they’ll be vocal about their approval or opposition to the decisions that you make. It’s absolutely possible to take actions that cross the line for someone and he or she will leave the party, or even decide to attack you.
From a player perspective, there’s the freedom to play the game in any which way you want from an alignment perspective. In dialogs, there are plenty of choices to be made, from heroically good to patently evil and the different shades in between. Added to that, there are unique options to be had from a player race or class point of view that fit within the good/neutral/evil perspective. As you would expect, a drow will get different options compared to a Paladin of Tyr for instance. For sure, the world will react to your actions, and the choices you make, since these will in some way define you. For example, Astarion is a vampire spawn and when you play him, you can try and hide this from the party. But if they find out -because, well, you might try to bite them as they sleep- they will obviously be shocked and unless you manage to handle the situation with the necessary tact and diplomacy, you may just find you’re left behind companionless.
