Phobias

Phobias (named after Phobos, which he is proud of) are a fear of various things. Demigods of certain gods have phobias, based on there parent's past.

Acrophobia
Children of Hephaestus possibly have acrophobia, fear of heights. Likely due to the fact that he was thrown of Mount Olympus.

Arachnophobia
Children of Athena have arachnophobia, fear of spiders. Due to the fact Athena had a bad experiance with Arachne. She vowed all her children would be afraid of her and her minions.