Final answer:
In the book 'Red Queen' by Victoria Aveyard, Darrow realizes that Titus is a Gold and has been working against the rebellion.
Step-by-step explanation:
In the book 'Red Queen' by Victoria Aveyard, Darrow comes to realize that Titus is a Gold. As a former Red himself, Darrow discovers that Titus has been secretly working against the rebellion, betraying his fellow Reds.
This revelation shocks Darrow and adds a layer of complexity to their relationship.