Again, it's Larian's style and everything has to be absolutely so special...
A vampire emo, a githyanki princess or something like that, a human that had sex with a god, another that has a pact with a demon (being a warlock won't necessary lead to such special stories... Hello custom warlock). The most usual companion is probably Shadowheart but I'm sure they have surprises for us... And what about Karlach that is probably going to be another companion...
I really miss the old BG companions... Their story was not deep enough for a new game but their background look plausible.
I fear that in BG3, it's going to be another overdose of originality.