Do they have a specific character? They have a specific history that is for sure. But their definite character gets decided by the player, not Larian.
If you question the dreamer, it is up to you do decide, how far Sebille will go, it's not decided by the game it selfs, otherwise it would be more like walking a predefined path.
Comparing Larian with Bioware is completely ridiculous. Not sure how Larians budget is for D:OS2, at least 2 Million and surely some of their own investment, but games like Dragon Age have surely a much bigger budget, 5-10 times bigger I would guess. Even so numbers are hard go get by, the estimate ist 20-40 Million.