Eddy finds great comfort in animals; he's good with them, and his pet minding business soon takes off as owners recommend him. This leads Eddy to becoming more than just a dog walker to one family as their complicated set of circumstances mean they come to rely on him, and in a way, he on them.
Kate de Goldi has a facility for, and no doubt fascination with, rich language and this plays out through Eddy, influenced by Brain.
With his love of literature and classical music, Eddy is an old soul, but tempered with the right and normal concerns of young people: love, sex, beer, and the teenaged boy's physical inability to give voice to a feeling. Circumstances contrive to make Eddy spill the emotional beans, and there are many of them.
If an eddy is an area of swirling water that forms behind an obstacle, like a boulder in a river, then this boy is that. We'll travel with him, whilst he overcomes.