The arrival of a new baby often heralds many changes in the household, and the impact is arguably the greatest on the newly promoted big sister/brother who has no choice but to adjust to these sudden and life-altering upheavals.
In Peter’s Chair, the eponymous piece of furniture is used as a metaphor for Peter’s fear of being displaced by his baby sister Susie, when it is the only piece of his old furniture that has yet to be repainted for her. As a result, he reacts by rebelling — albeit only for only a short time — the only way he can think of to do so, by running away with his chair.
Anyone who has had to welcome a new sibling will empathise with Peter, and feel reassured by the fact that they are not alone in having mixed feelings. The way that Peter works out his feelings on his own is also admirable, and his change of heart reflects his growing maturity.