That Percy attributes his fear of small, enclosed spaces to his ADHD shows that he hasn’t entirely shifted over to thinking about his disorder as something related to being a demigod. When the monsters reveal themselves, it becomes clear that Percy isn’t experiencing ADHD-adjacent claustrophobia: he’s legitimately sensing monsters and is scared for a valid reason. The woman and the Chihuahua show that they understand the power of friendship, as they wait to get Percy alone, when he’s more vulnerable.