In fact, perhaps the best way for us to make our custom PC special and central to the game is to kill off ALL the origin characters at the earliest possible moment. But of course Larian's made sure that cannot happen either, right? Because then we wouldn't have a viable party!
The best way in my opinion would be if the MC was the only one to have dreams and special powers.
Tadpole 1.0 = become a mindflayer or die Tadpole 2.0 = become a true soul Tadpole 3.0 = true soul + dream + powers
That's a great idea. In NWN2 the MC had the Shard, and the powers that came with it. In the sequel Mask of the Betrayer, the MC had the Spirit Eater. Being special made the MC the central character.