In the opening moments of the play, Priestley presents Sheila as an immature materialistic character despite the stage directions telling us that she is in her early twenties
Sheila refers to her parents as "mummy" and "daddy", an infantile immature mode of address which is reciprocated by Mr and Mrs Birling who refer to Sheila as both a child and childish
Early in Act 1, Gerald inquires of Sheila "I've been trying long enough, haven't I?" but it is Mrs Birling who interrupts and replies in Sheila's place
It is clear early on that Sheila is not treated as an equal by anyone, reflecting how women were treated as inferior to men at the time the play was set
The sarcastic "You're forgetting I'm supposed to be engaged to the hero" cuts through Gerald's attempt to romanticize the story of his interactions with Eva
The maturity behind Sheila's cool returning of the ring as opposed to a tantrum at the end of Gerald's confession implies to the audience that this is a woman who is now not governed by her emotions but by logic and reason
Priestley seems to be suggesting that the audience should aspire to be like Sheila - they should own the mistakes they've made and make others accountable for their own mistakes too
Priestley presents Sheila as a character who quickly learns the Inspector's message of social responsibility, unlike her parents who when they think they've got away with it laugh and encourage their children to do the same
The contrast between Sheila and her parents can be interpreted as Priestley criticizing the behaviour of the older generation who are fixed in their ways
In Act 2, Sheila addresses Mrs Birling as "mother" and Mr Birling as "father", a symbol of how she has matured from the childlike Act 1 address of "mummy" and "daddy"
In Act 2, Sheila interrupts and answers a question directed at Mrs Birling, telling the Inspector "Yes, she is. Why?" when he asks if Mrs Birling is a member of the Brumley Women's Charity Organization
Priestley uses repetition as a technique, with Sheila mirroring the language used previously by the Inspector when she talks about "fire and blood and anguish"
This mirroring of language is Priestley's way of showing us how Sheila has not only learned the Inspector's viable lesson but has in some way taken on the role of the Inspector himself
Through his presentation of Sheila, Priestley encourages the audience to challenge conventional thinking and to question the behaviour of others, holding those to account who have power over us even if that means rejecting those who are close to us and rethinking our own world views
If Sheila can so dramatically transform from a selfish shallow creature to one who now challenges others and cares about social responsibility, then everyone in the audience can also transform in the same way