Behavior and Personality
Catherine is friendly and amiable, warming up to the player right away, and offering them advice and directions, either through talking to her on the boat, looking at her notice board on the cabin window, or communicating with her via a radio somewhere on the player character's suit.
Though she cannot swim and fears swimming (hence why she wears a safety vest all the time), there is a camera on the player's diving suit somewhere that she receives video feed from, allowing her to see all that they are seeing, and thus provide them with directions and instructions.
Catherine is very intelligent and intuitive, and appears to have the ability to understand animals on a basic level; She can read their body language and vocal signals to translate what she believes they are saying, as was first displayed in the presence of an African Penguin that climbed up onto the player's boat. She also has extensive knowledge about artifacts and oceanic archaeology, as can be surmised from the information she provides the player with whenever they recover a salvage item of importance or discover a unique area, though she often contacts people who know more than she does in order to give the player more information.
Catherine was fascinated by ocean life from a young age. Her father, Patrick Sunday, was a scientist and sailor who died whilst searching for the Ancient Mother (presumably by drowning). Catherine's goal is to find the White Mother and finish her father's quest, but her inability to swim held her back until the player character came along. It is unknown where her fear of swimming came from, although it can be assumed that it might have had something to do with her father's death.
- Catherine has a fairly large fan base. Her kind and friendly personality was often seen as a very welcoming factor to the game. When Endless Ocean 2 was announced, many people were eagerly anticipating her return however she was replaced with a similar looking shorter girl named Oceana. In early screenshots Oceana was mistaken for Catherine without her glasses, some people even thought it was Catherine's cousin. Her removal from the sequel angered many fans and Oceana does not appear to have received the same amount of popularity.
- Catherine is often criticised for the uselessness of her comments. Normally when talking to her, she comments upon the current mission the player should focus on, or she makes a randomized comment or states a random fact. Game reviewers stated that Catherine looked too robotic and took away from the game's atmosphere. The critics also complained about her pointless dialogue. For example, when the Idol treasure is reconstructed she says something along the lines of "I have a feeling something bad will happen if I reconnect these pieces... Oh well, let's do it anyway".
- Some speculation has arisen as to why she was not featured in Endless Ocean: Blue World. One rumour is that she was fired for being unable to swim and be of more use, whereas another rumour suggests that her findings concerning White Mother have led her to fame and fortune, meaning she no longer needs her job as a secretary.