Baby Maddie's mother (SPOILERS)
When I watched the two scenes early in the movie when the baby's mother Carolyn was a drunken, irresponsible, and seemingly unloving mother, only interested in being confirmed as sexy by a man, I thought that she seemed irredeemable and was a stock villain for central casting. Later, when she sobered up and found herself frantically trying to find the baby, her character got the added dimension of someone whose husband would leave her if she didn't seem responsible and loving. Still later, she is presented as actually caring about her child.
I would have bought this storyline more if there had been small indications in the earliest scenes that she had a maternal instinct hidden inside. For example, she could have pulled Maddie away from the balcony, spilling her drink on the way. Or when she came back to the hotel after her failed date, she could have kissed Maddie before falling into a stupor.
I just wanted to believe that Carolyn's transformation didn't come out of nowhere.