why did teresa betray thomas

Teresa betrayed Thomas because she was forced and manipulated by the organization WICKED. WICKED threatened that if Teresa did not cooperate and betray Thomas, they would kill him. Teresa's betrayal was an act she had to perform under pressure to save Thomas's life, though it caused a lasting rift between them. Despite her betrayal, she often tried to warn Thomas of dangers and showed regret for her actions. The entire betrayal was also intended by WICKED to make Thomas truly and absolutely feel betrayed, as part of their experimentation and control. Teresa's complex position shows she cared deeply for Thomas but was trapped by the harsh demands and threats from WICKED.