I know from watching one of the trailers, there are some splicers that wont attack you on sight.
I clearly remember in one of the latest trailers, you came out of a vent, and one of the splicers was drinking some water off the floor, and started talking to you starting with "Raptures gone to hell!"
I'm curious to see if not every enemy you come in contact with is a shoot on sight enemy.
*SPOILER ALERT!!!!*
In the game, it tells you that you were created in Rapture, and was forced to leave when Atlas and Ryan began trying to get a hold of you.
'Would you kindly' brought him back. I wouldn't be surprised if she reconises you...
BTW, She does try to stop you escaping, because Atlas tells her to. Atlas holds the ADAM, not Ryan.
you were originally from rapture so it depends on how you decide to take what she said