To the media literate it is plain to see that characters embody values, ideals. The function of a character is to lead perception into patterns, to express power structures, to resonate. Characters are not people; they are not real although they signify the real. A character points to ideologies and mythologies, cultural phenomena. Characters can be read (as they are meant to be read) as metaphors, paradigms, archetypes. Characters are defined not by being individuals but by the functions that they preform - characters are not who they are but rather what they do.
We discussed Lagos Egri, who stated that characters needed dimension. We, as a viewing audience, must know why they do what they do and "who" they are. On television characters are established quickly and repeatedly. Their dimensions are created threefold; physiologically, sociologically, and psychologically. Physiology being the characters sex, gender, age, appearance, defects and the like. As for sociology, that includes class, occupation, invocation, religion, political affiliation, etc. Psychology is the less obvious of the three, being sex life, moral standards, character, temperament - what makes the character who they are that we cannot see or easily deduce.
We continued to discuss character archetypes - the hero, villan, donor, dispatcher, false hero, helper, and the princess and her father. We also discussed Vladimir Propp who proposed that character functions are stable, independent of whom and how they are fulfilled. Simply put, an archetype exists as it always exists regardless of the character that is filling it. There are necessary conventions to character archetypes that the character must follow. One hero, though in a different body than another, is essentially the same unless that hero is not actually a hero.
Characters themselves are a fascinating study, and though this entry simply scratches the surface I hope it provides a decent overview of a few key ideas that are pertinent to understanding characters.