The outer layer of the individual includes lots of different details that help to describe who they are, but at the same time it still holds characteristics that are common to almost everyone. If you look beneath the surface (outer layer) of the same person though, you"ll discover things about the person that they might not want to necessarily share with everyone. These things that the individual is keeping somewhat hidden are usually only revealed to others that the individual feels that he/she can trust. The inner most part of the individual is what makes up their personal values, who they think they really are, as well as other things that the person feels deeply about. This "core layer" is that persons very private domain. It is this domain that is not shown to the outside world but at the same time, what is affected here tremendously affects the persons surface layer. Sometimes people that are extremely close to a person may not even know the individuals closest kept secrets.
According to social penetration theory, a relationship will work out or not work out based on the cost-benefit analysis that each person feels they can get out of the relationship. Right after a person meets someone else, they will sort out the good and the bad points of having a relationship with them. They will ultimately come up with a answer on if they are going to pursue a relationship with the other individual or not. If the person believes that they are going to receive benefits that will ultimately outweigh the costs of exposing more of themselves to someone else then the social penetration theory will start to work.
Irwin Altman and Dalmas Taylor, who are both originally the minds behind Social Penetration Theory go into a great deal of detail in their book Social Penetration: The Development of Interpersonal relationships. In it they describe how Social Penetration affects people in relationships with other people as far as the way in which the relationship is developed over time.
