Yeah the saviour/good ending seems to be the one they have gone with. The Big Sister is one of the original Little Sisters, I am not sure if she actually ever left Rapture or was a stray left behind but I believe the story is she has been leaving Rapture and stealing little girls and bringing them back to Rapture. Or at least the marketing seems to suggest that as they say that little girls have been going missing.
If you look at the original teaser on the PlayStation 3 version of the game it shows that the original Little Sisters are now in their teens. They have either done that to show that time has passed since the original or they will figure into the events of BioShock 2.
If you look at the original teaser on the PlayStation 3 version of the game it shows that the original Little Sisters are now in their teens. They have either done that to show that time has passed since the original or they will figure into the events of BioShock 2.
Comment