Dr. Frederick Chase is the mortal father of Greek demigod, Annabeth Chase, and her half brothers, Bobby Chase and Matthew Chase, as well as the husband to Mrs. Chase. He is the brother of Randolph Chase, and his late sister Natalie Chase, and the uncle of Magnus Chase.
When Frederick Chase was young, he was a brilliant man who wanted to go to college, but he didn't have enough money. However, his brilliance and wit gained the attention of Athena, the goddess of wisdom. She helped him get into Harvard University and he finished his studies successfully with her help. Their relationship eventually ended on good terms and Athena sent him their daughter, Annabeth Chase. She appeared on Frederick's doorstep in a golden cradle carried down from Olympus by Zephyros, the West Wind. She was considered a "brain child" like all other children of Athena, which means that they were born from the thoughts of the goddess, which makes them the only demigods to be claimed at birth. Frederick originally wanted Athena to take Annabeth back, but she sternly told him that demigods must be raised by their mortal parent. Frederick then subsequently married an Asian woman and they had two sons: Bobby and Matthew.
When Annabeth was seven years old, Frederick visited Randolph and Natalie during Thanksgiving, and the three Chase siblings ended up getting into an argument, resulting in Frederick and Annabeth leaving, with him never visiting or speaking to his siblings since.
Frederick's family was frequently attacked by monsters, due to Annabeth being a demigod. Annabeth thought that her mortal family resented her for this, and eventually, some time after Frederick's quarrel with his siblings, a seven-year-old Annabeth ran away. She later made it to Camp Half-Blood with the help of Thalia Grace, Luke Castellan, and Grover Underwood. From camp, Annabeth would talk to her father mostly in letter form, as phones were too dangerous for a demigod. Mr. Chase would occasionally ask her to return home, but Annabeth always refused.
Annabeth eventually returned home at her father's request, but left when she saw that nothing had changed. Her father then sent her his Harvard college ring, in hopes that she would remember him by it, and be convinced to come home. She started to wear his ring on her necklace with the beads that she earned every year at Camp Half-Blood.
Annabeth accompanied Percy Jackson and Thalia Grace to assist Grover with two new demigods (Nico and Bianca) at a military school. Annabeth told Percy that her father was moving to San Francisco, but that she was unsure whether to go because the area contained the Titan base of Mount Othrys, and was therefore thriving with monsters. Annabeth, during the mission, went missing and Percy went on a quest to save Lady Artemis to find her.
In San Francisco, Thalia suggested they visit Frederick Chase for transportation. The revelation of his daughter's disappearance shocked Dr. Chase, who agreed to give the questers his car, which they unintentionally destroyed. After rescuing Artemis, the group were gravely endangered by a fleet of monsters, but Dr. Chase, ignoring the warnings given to stay away, flew in on his plane, a Sopwith Camel. Using special bullets he created out of some of Annabeth's Celestial Bronze weapons, he shot and destroyed several monsters, ensuring the others would escape.
Frederick was relieved that his daughter was safe and reminded her she still had a home with him just before Annabeth left with Percy and Thalia on pegasi.
Annabeth remembers the time she used to hate her mortal family, and says it was stupid of her to think that way for so long. She then remembered her uncle Randolph and cousin Magnus living in Boston, whom she hadn't seen for eleven years, due to her father not getting along with Randolph after their quarrel.
Eleven years after his quarrel with his siblings, Fredrick and Annabeth are looking for his sister's son Magnus, after being contacted by Randolph that Magnus has been missing for two years since his mother's death. After Magnus' funeral he flies back to San Francisco.
Fredrick was mentioned when Magnus was looking at a picture of him and his siblings.
Magnus states that Fredrick was contacted by his brother's lawyer after Randolph died.
Frederick Chase is a fairly normal mortal, though with a genius-level intellect. His genius caught the eye of Athena, who was enchanted by his wisdom. He most likely caught her attention by his fascination with wars and his love for airplanes. Frederick loves his daughter Annabeth very much, though he did not want her at first, but that is somewhat expected, since he didn't know that his friendship with Athena would result in a brain child, and when she came, he did not have time to take care of her, as he was not originally prepared. Despite this, Frederick has attempted to be on good terms with his daughter. When she ran away at the age of seven, Frederick was heartbroken until her return several years later. Percy once described Dr. Chase as an "excellent mad scientist" because of his experiment with celestial bronze bullets.
Frederick is described as a handsome, athletic, middle-aged man with intense brown eyes, and sandy-colored hair, like that of his daughter Annabeth.
Frederick's elder brother, with whom he hasn't spoken with after their family quarrel 11 years before The Sword of Summer. However, he still cares somewhat for his brother, as he reconnected with Randolph and traveled to Boston with Annabeth after learning of Natalie's death and Magnus' disappearance. .
Frederick's late sister, with whom he hasn't spoken with after their family quarrel 11 years before The Sword of Summer. However, he likely still cared for his sister, as he traveled to Boston with Annabeth after learning of Natalie's death and Magnus' disappearance, as well as being described by Annabeth as devastated at Magnus' funeral, likely indicating that he has some degree of regret for falling out with Natalie and never getting the chance to reconcile their feud.
Frederick's twins sons with his wife Mrs. Chase.
Frederick's wife, and Bobby and Matthew's mother. She is the stepmother of Annabeth. She married Frederick, when Annabeth was five. They love each other very much.
Frederick's daughter with Athena goddess of wisdom, warfare and crafts. He was surprised that he had an infant daughter to care for, and tried to get Athena to take her back, but she sternly told him that demigods must be raised by their mortal parent. His family was attacked by monsters due to Annabeth being a demigod. Annabeth eventually thought that her mortal family resented her for this, and ran away. In The Titan's Curse, it seems her relationship with them is getting better, and by The Last Olympian she seems to be living with them again (though, this is not for certain because she is going to go to a school in New York near Percy's, and her family lives in San Francisco).
His brilliance and wit drew the attention of Athena. She helped him get into college, and he finished his studies successfully with her help. Their relationship eventually ended on good terms.
- When the Sirens sang to Annabeth, she saw her father and her mother, Athena, together again, and happy. She saw Luke sitting next to them, patting the ground next to him, asking her to stay.
- Frederick is a professor at West Point and teaches American history.
- Frederick "plays with toy soldiers" according to Percy. In other words, he makes models of WWI battles. Although, he is said to play with them, making the shooting and explosion sound effects and other things along the line of that.
- Dr. Chase also appears to be able to see through the Mist. While on Mt. Tam, he successfully shot Luke's monster army with his modified bullets without harming the demigods. He also saw Blackjack, Guido and Porkpie without any difficulty and questioned how the Pegasi could fly with their body mass v.s. wing span ratio.
- Thus he is the only mortal male in the series with the possible ability to see through the mist in the Greek/Roman books. Amir also has this ability in the Magnus Chase series, though unlike Frederick this ability was not something he was naturally born with.
- He is the only mortal parent of the Seven that is both alive, and never suffered any type of horrible fate or form of captivity.
- Notably, Fredrick is the only parent of the main(and mortal) protagonists in the Riordan franchise to both still be alive and not suffer any form of a cruel fate: Percy Jackson's mother was once kidnapped by Hades to use against Percy, Carter and Sadie Kane's mother was killed in a ceremony to free Bast, their father died several years later and merged with the god Osiris, Magnus Chase's mother was killed by wolves sent by Fenris Wolf to manipulate Magnus, Nico Di Angelo's mother was killed when Zeus destroyed the hotel she was in, Leo's mother was killed when Gaia tricked him into setting her workshop ablaze, Piper's father was kidnapped and driven mad by a giant, Thalia and Jason's mother suffered a mental breakdown and eventually died in a car crash, Frank's mother was killed in Afghanistan, Hazel's mother died when she sacrificed herself to stop the rising of Alcyoneus.
- His favorite movie is Roman Holiday.
- As being a professor in American and Military History, he is interested in collecting war souvenirs such as his Sopwith Camel biplanes from World War I.
- He has Swedish Ancestry, being a descendant of Swedish royalty.
- He is the only Chase sibling to still be alive. Furthermore, he is the only Chase sibling whose children are still technically alive.
- Fredrick is the only Chase sibling to have no connection with the Norse Pantheon.