Doyle is careful to present the characters’ Irish accent and colloquialisms accurately, thereby making the novel realistic.
Features of Irish language - Paddy learns Irish in school - and everyday speech are key elements in his writing.
Doyle’s use of dialogue changes depending on character and situation. Most of the characters speak in Dublin vernacular, but the language used by Paddy and his gang includes a lot more slang than the adult characters.
Words like “mickey” and “gee” for sexual body parts are typically used by children. Paddy’s tendency to overuse words like “brilliant” and “stupid” because of a lack of more sophisticated vocabulary is also typical.
Other characters – such as Mr Hennessy and the headmaster for example - speak mostly in the Standard English of educated men.