At first, Wendy is concerned about Peter's future and tries to convince him to think about growing up, but as the dialogue continues, she becomes excited about the prospect of living with fairies.

could you rewrite this like a 12 year old but keep it formal

Initially, Wendy is worried about Peter's future and tries to persuade him to consider growing up. However, as they talk more, she gets really excited about the idea of living with fairies.