The relationship between Theo and Kitsey parallels deception surrounding the entire idea of paintings in the novel. On one hand, Theo does not love Kitsey, although he considers her the best choice for a future wife. He has true love for Pippa, but is distracted by Kitsey’s relationship, which he knows will not work. Similarly, Kitsey is in love with Tom but does not disclose it until Theo finds her kissing him. When they talk, they discover that they have similar issues and proceed to convince each other that the best recourse is to remain together.
On the other hand, there is deception in the paintings and antiques businesses, including the one being operated by Horst. He is an associate to Boris, and is also the person who is holding The Goldfinch as collateral for a sum of money lent to Boris. Horst is not aware of the exact value of the painting he is holding, but feels that he can still hold it as security. Similar deception is evident at Hobie’s workshop, where Theo resorts to selling restored antiques as originals. After being in the antique business for some time, Theo discovers that it is ultimately the buyer, rather than the seller, who determines the value of an artwork. Deception is also extended to The Goldfinch, whereby Theo has always believed that he has been in possession of the painting, when — in reality — he has been keeping a wrapped textbook.