I think people have a problem with one.
In fact, there is no single main character in the game, such as in WotR.
The game is designed from scratch for multiplayer, which means that instead of one single hero, we have a whole team.

Another thing is that you can't make a custom character equal to Origins. This is simply not feasible without turning the custom character into another Origins character (this time in the ligth version).
The Origins system allows you to create characters that have an established place in the story, with a certain personality (although fluid).
From what I've seen, Origins characters have quite a lot of unique interactions that would not be possible for non-standard characters, at least not without a huge amount of work or cutting a large number of choices in character creation.
Probably the only characters it would be possible with are Astarion and Lae'zel (mainly because I didn't see what these characters have)