Radio characters are subject to most of the rules that apply to characters in general. However, radio offers additional opportunities for characterisation and imposes additional constraints on it.

WHAT MAKES GOOD CHARACTERS (IN GENERAL)?

• They make "good speeches".
• Their use of language is consistent with their background and personality and with the conventions of the piece. They need not necessarily be eloquent, but they must be sufficiently articulate to enable the reader/listener to understand them.
• The writer’s representation of them inspires listeners/performers to breathe life into them, to make them "credible".
• They evoke some response in listeners/performers.
• Listeners identify with some aspects of their personalities, even if they are not likeable characters. For example, a cruel character may enable readers to recognise some of the same cruelty in themselves. And even the most cruel characters may have some redeeming features.
• They have depth, perhaps hidden depth, of character. They are complex, many faceted, not just two-dimensional, not simply good or bad.
• They have a history.
• They have some mystery.
• They make the listener want to understand them.
• They have diverse personalities and/or "voices", such that each assumes a distinct identity in the minds of the reader/listener. Perhaps their character is so strong that the listener is able to predict their actions to some extent.
• Perhaps their behaviour is sometimes unexpected. Perhaps they act "out of character" at times.
• They undergo some development during the course of the work.
• They conflict with one another and perhaps within themselves.
• They engage with the plot, contributing to its development and perhaps revealing some aspect of their character in response to features of the plot.
• Perhaps they help us to imagine how we might respond in certain situations.

CHARACTERISATION OPPORTUNITIES FOR RADIO WRITERS

• The absence of any visual dimension allows the writer freely to explore characters that might not easily be portrayed visually without significant production resources (costume, animation, special effects, etc). Accordingly, animals, ghosts and even inanimate objects may be readily brought to life on the radio.
• Characters may become suddenly older or younger more readily than in visual media, notably theatre.
• Visual clues as to characters' appearance, actions or situation, which have a significant bearing on the plot, may arguably be concealed more effectively on radio than in visual media.
• Radio writers have much greater control than, say, novelists, in the matter of how their characters are to be perceived by the audience (accent, tone of voice, emotional range, etc)

CONSTRAINTS ON RADIO CHARACTERISATION

• Radio characters must be particularly well differentiated so that listeners can identify them easily.
• Characters must be relatively few in number or else established individually over time (as in 'The Archers') if their identities are not to become confused in listeners' minds.
• The compressed timescales of radio productions and, in particular, the shortness of programming slots, militate against the complex characterisations that are the stuff of good literature.