Who is Amelia from The Lock Artist: A Novel and what is their importance?

Amelia is the girl Mike loves, and he begins opening safes to help her father and Amelia, by extension. Amelia is first mentioned when Mike draws his day for her after stealing diamonds from the house in Connecticut, and he mentions her again when he describes breaking into the Marshes' house because he sees her for the first time in a self-portrait she drew in her bedroom. Amelia confronts Mike while he digs in the Marshes' backyard, accusing him of being able to talk. Mr. Marsh and a locksmith make Mike unlock the Marshes' backdoor, and that night, Mike draws a portrait of Amelia and plans to give it to her. At Wesley's house, Mike and Gunnar rob the safe and manage to sneak past the multiple alarms to rejoin Lucy outside and return to the club. After failing to open a lock with serrated pins at the Marshes the next day, Mike's day worsens when he sees Amelia and her friends drawing him. He buries the portrait in the pile of dirt, but that night, he retrieves the portrait, breaks into the Marshes' house and leaves the portrait on Amelia's dresser. Since she does not tell her father, he draws a comic strip portraying their first meeting the next night, and he and Amelia begin exchanging comic strips as a means of communicating.