One can argue for the counter point that having well written personalities for characters is what makes or breaks the immersion though. It's true interactions between 2 player-controlled characters is an interesting idea in theory, one that hasn't been tried in games yet as far as I know, but you shouldn't forget that the point of an RPG is to roleplay and that requires you to be put into a specific role. Either by having all characters defined and written with only situational choices (Torment, Mass Effect, or Dragon Age: Origins style) or by giving the player an defacto Avatar (Baldurs Gate, NWN) who has infinite choices, but a central fate that needs roleplaying "around".
To me, one of the driving forces behind playing RPG's is to explore the characters and personalities someone else has written. I don't know how to put it exactly... but it is to me very jarring to go into a dialog where I am both parties when those 2 parties are essentially both identical blank slates. As you say.. hardest thing in writing is make a character that's not your own personal meme.
I think maybe I should say what my point is.. it is that I think (And this is purely my personal opinion) that a good RPG immerses you into the world by making you care for not the world or story, but for specific characters. And as I said, the option to play 2 characters at once is not the problem, after all I "played" 6 in Baldurs Gate 2. The problem is neither player character in Original Sin has a defined character or personality from which we can start shaping ours.
This is why so many RPG's implemented "history/personality" of their characters as a choice, in order to shape the role in your head, most players *need* a defined character. There can be choices of course, but the choice "no history/personality" should never be given to a player.
Either way, this game will be moddable and that means I can do what I want with the OC once it's out.. so in my mind I am pretty set on changing the 2nd character to something else. I think a huge chance was given away here to give players OPTIONAL asymmetry between controllable characters. Ie, 2nd character could have been some magical wolf or whatever else you might envision with unique parts in dialog etc. And thus a dialog between the 2 might really be roleplayable without the same problems that are caused when you are roleplaying essentially 2 identical dudes/gals. (that's at least for me, the problem with 2 playable "player" characters)
Mhh, I wrote again so much..
I don't know what Original Sin offers when it's complete, so don't take this the wrong way. I am talking about theory at best, not to complain ;p
