It is the ultimate metaphysical question–who are we ? There are biological, existential, philosophical, spiritual dimensions to it. But one aspect of self that seems compelling to me is how we are different with different people.
We seem to react to individuals when we are in their presence. In some way we pick up cues from them and create a bond of some kind which changes, in sometimes subtle ways, who we are in the moment.
Several quick examples are illustrative: how do we act around our parents versus our contemporaries. Perhaps young individuals learn this intuitively. They come into conflict when they forget who they are with.
The classic example is the college student who returns home from school for a vacation and blurts out to his Mother, "could you pass the fuckin peas!"
More subtle examples can be noted when we are with different groups of friends. We usually sense their interests, sense of humor, attitudes and can morph ourselves in order to facilitate the connection.
In our particular professions and lines of work we may create a persona, a mask, which we deem necessary in order to perform our roles.
Then there are some individuals who seem to enjoy being contrary. It is not clear why except to bring attention to themselves. By sensing the flow of personalities or conversation, they clearly go against it. This often brings a sense of unease to others who are seeking a more tranquil interaction.
Woody Allen's film ZELIG was a humorous but enlightening attempt to describe an individual so intent in "fitting in" with others that he literally could change his skin color when jamming with an African American jazz band.
In addition to a basic personality which has evolved throughout our lifetime, it does seem that we possess a flexible, amorphous aspect of self which can and does modify itself according to those around us.
It is fascinating to observe ourselves when we are with others. It seems as if we do become somewhat different people when in the presence of others. It is as if we form a new self which has an existence, however, transient of its own.
Sometimes this self works for us, at other times it may work to our detriment. I recall a former medical associate whose persona as a physician was rather stern and harsh. Patients complained to me that he often frightened them. Yet when out socially, he was totally different–friendly, light-hearted and engaging.
Somehow he never picked up on the difference, nor perceived the reaction from others.
In any case, don't become so self-conscious that in inhibits the phenomenon. Go with it.