I know all that, but this isn't a table with an actual DM that can work on the fly and talk to their players to weave everything together as it goes. This is a video game that was completed and handed over to players, and so trying to make a major NPC that only possibly exists in any playthrough, and make that NPC personally important to the character as well is something I don't believe Larian would do.
The game would not have a warlock NPC that exists only for one playthrough but it can have warlock NPCs or enemies you encounter as you play through the game...not necessarily tied to you being a warlock or anything like that...just characters you can find at certain locations or encounter during certain missions.
