I only played with the Origin character mod for a short time before giving up but there is a problem with trying to subvert the story -- the conversations on ground triggers. At certain points the origin characters will make comments that the player has no control over and those comments are in line with the original design.
There are a couple with Tav as well. If you go the part of the grove where the tiefling bets you 10gp that the goblins will kill her you can find a trigger where LZ will express contempt for the weakness of the tieflings and Tav will rebuke her saying something like "lay off these are desperate refugees not fighters":
Which is probably what my Tav would have said but it annoyed me that I didn't get to choose a substantive RP option.