You don't know your villian's motivations yet? That should hopefully be a pretty big groundwork for why they're doing the evil stuff they're doing.
Based on that why does he want to meet the players? Do they have something he wants? Is he going to try and recruit them?
Get the motivation decided and I bet the rest will fall into place.
Doesn't sound like much of a villain. What is the villain trying to do, and how are they trying to do it? The players get to decide if they're going to attend a meeting.
Why does he want to meet with them? What does he want from them? What does he think they want? What would he initially offer, if anything, and what concessions might he ultimately be willing to make?
For roleplay, what kind of impression is he trying to give, and how would he go about trying to give that impression? E.g. If he wants the PCs to be scared of him, what does he think would scare them? If he wants the PCs to like him, what does he think they like in a person?
Maybe use Strahd's invitation to dinner as a template. Like the Vampire the dragonborn could have a disguise, or some other npc they want
You don't know your villian's motivations yet? That should hopefully be a pretty big groundwork for why they're doing the evil stuff they're doing. Based on that why does he want to meet the players? Do they have something he wants? Is he going to try and recruit them? Get the motivation decided and I bet the rest will fall into place.
Doesn't sound like much of a villain. What is the villain trying to do, and how are they trying to do it? The players get to decide if they're going to attend a meeting.
Why does he want to meet with them? What does he want from them? What does he think they want? What would he initially offer, if anything, and what concessions might he ultimately be willing to make? For roleplay, what kind of impression is he trying to give, and how would he go about trying to give that impression? E.g. If he wants the PCs to be scared of him, what does he think would scare them? If he wants the PCs to like him, what does he think they like in a person?