Aidan Cain is the second important character in the novel Enchanted Glass. About 12 years old, he shows up in a taxi at Melstone House at the beginning of Chapter Two. He has just run away from the foster home he was sent to after the death of his grandmother, Adela Cain. The foster home wasn't great, but it wasn't really that bad. However, Aidan found himself being watched and followed by Stalkers -- three different types of supernatural beings, some tall and warriorlike, others more like aliens with antennae on their heads. He feels very certain they mean him no good. And his grandmother told him before she died that if he was ever alone and in trouble, he should find his way to Mr. Jocelyn Brandon at Melstone House, who would protect him.
Unfortunately for Aidan, when he arrives there, he finds that Jocelyn has died recently, and there is a new owner in the house -- a Mr. Andrew Brandon Hope, known locally as 'the professor.' He is terrified and ashamed of being in the wrong place at the wrong time among strangers, but Andrew treats him kindly, and it happens also to be the day that Mr. Stock and Tarquin O'Connor arrive bringing Stache with them to meet Andrew, so Aidan is able to sit quietly at the side and observe everyone interact, including, after awhile, Mrs. Stock's nephew Shaun, who is also being pushed on Andrew as a potential employee.
When Andrew eventually tells Mrs. Stock to make up the spare room for Aidan to stay in until they can find the best place for him to be, Aidan is hugely relieved. And he soon makes friends and discoveries and finds that he can be useful in Andrew's life.
For example, Aidan has the habit of looking at the normal world through his glasses, but taking those glasses off to scrutinize them carefully and to see the essence of a person or place, especially where magic is concerned. And he expresses that habit to Andrew, who is able to discover that he does the same thing, only has never been conscious of it before. Andrew also finds his memories of his own childhood getting clearer and clearer as he watches Aidan live his own life.