Final answer:
The prefrontal cortex is likely affected by the brain tumor in Justicia, causing changes in personality, mood, and behavior.
Step-by-step explanation:
The brain structure likely affected by the brain tumor in Justicia is the prefrontal cortex. The prefrontal cortex is responsible for planning, judgment, reasoning, and working memory. Damage to this area can result in changes to personality, mood, and behavior, which aligns with Justicia's initial symptoms of excessive fear and anger.