|“||You're going to outshine me someday, Piper. They're going to remember me as Piper McLean's father, and that's the best legacy I can imagine.||”|
Tristan grew up as a poor child in a two-room house in Oklahoma with his father Thomas McLean. His mother has never been mentioned. His father would talk about the old Cherokee tales that he knew, such as the snake song, the constellation of an Armadillo, and Ghost Country, a place where you could talk to the dead. However, while interested in the stories, Tristan never truly believed them.
Tristan eventually met and fell in love with the goddess Aphrodite. However, Aphrodite never revealed to him who she really was, as she felt he would be unable to handle the information that gods were real. The two eventually had a daughter together named Piper McLean, at her grandfather's suggestion. Tristan liked the name as Piper had a strong voice, and would occasionally call her Pipes. Shortly after, Aphrodite left Tristan without a word or ever revealing her true identity. Tristan took it hard, but still raised Piper as best he could.
Years later, Thomas became ill with lung cancer. Tristan could not afford the payments for the treatment and his father eventually succumbed to his disease. After that, Tristan became an actor and eventually gained the lead role in a film called King of Sparta. While him and Piper would joke about how silly the poster was, the movie itself became a big hit and rocketed Tristan's career. He went on to play roles as a Latino teacher, an Israeli spy, and a Syrian terrorist in a James Bond movie. Piper helped him research for a role in a movie involving Greek mythology by helping look up information. However he would always turn down Native American roles, including a several million dollar offer to play Tonto in a Lone Ranger film. When Piper asked why, he claimed that he felt Native American roles were to close too home for his liking, though, if the perfect Native American role was offered he says he may accept.
Because of his acting career, Tristan tried to keep Piper at a distance so she would not be caught in his busy celebrity life. Piper however saw this as him avoiding her and began stealing things to gain attention. While the things were normally small, Tristan did not know how to handle the problem and would send her to different boarding schools. Eventually, Piper stole a BMW car right before Tristan told her they were going on vacation to Grandpa Tom's cabin, and Piper hid the information from him. The car owner pressed charges and Jane, Tristan's secretary, worked out a deal, resulting in Tristan sending her to the Wilderness School.
Tristan McLean is held hostage by the giant Enceladus, who blackmailed his daughter, Piper, to lead a group of demigods into a trap. Although he is not seen for most of the book, Piper has many flashbacks to times when they were together.
The first time Tristan is brought up is when Leo made a comment about how if the popular girls at the Wilderness School knew who her father was, they would be worshiping Piper and saying things like "We're not worthy." It is later learned that Tristan is a popular movie star and has played many important parts, one of his first being the King of Sparta. He thought the movie poster of the film looked funny, but it has became very popular and has sold many copies. When Piper arrived at Camp Half-Blood, there was a poster of him hanging up on the wall, but it is later torn down by Drew after learning that Piper was his daughter.
In one of Piper's flashbacks, she remembered when he told her why he did not play any Cherokee parts, as it would be too close to home. He also does not believe in any god(s) because if he knew they did exist, he would always blame them if things went wrong. In another flashback, he found out from his assistant Jane that Piper stole a BMW, but instead of talking to her about it, he goes along with everything that Jane says and sends her to the Wilderness School.
Eventually, Medea used charmspeak to control Jane, who told Tristan that his daughter was in danger and he needed to go to San Francisco to save her. He does, but is captured by Enceladus and chained. Piper has a dream about his capture and tries to call him with no success. When she calls Jane to find out where he is, she brushes her off and claimed that even if she does not know where he is, he would vanish sometimes, so she had yet to call the cops or file a missing persons report.
Piper, Jason Grace, and Leo Valdez make it to the lair of the giant Enceladus to save Piper's dad, who has been chained and beaten in the far corner of the room. While Piper sets him free, Jason and Leo fight off the giant and his Earthborn. As the Earthborn hold a grudge against Jason, Enceladus says that McLean is Jason and the ogres want to kill him. After Leo had killed most of the Earthborn, the most powerful charges at him, but Piper for the first time uses her knife and kills the monster. The heroes manage to win the fight with some help from Zeus. Tristan is lifted to a nearby airport where he is almost driven insane by the idea that gods are real, and from the torture the Enceladus inflicted on him.
Using the potion given to her by her mother, Aphrodite, Piper erases her father's memory of the days he was imprisoned. Coach Hedge takes care of him and acts as his new bodyguard and "life coach" while he recovers. Tristan also fires Jane after she failed to call the police while he was missing. He hires Mellie as his new assistant soon after. Tristan gives the Park Service in the Bay Area a new helicopter (though probably set up by Coach Hedge or Mellie) and hires the ranger pilot, who loaned Leo, Jason, and Piper her helicopter, to fly for him. He calls Piper using a webcam while she was at Camp Half-Blood and wants to know if she likes her new school (having forgotten about her being a demigod and the gods themselves), which she says she does.
Whilst in Pylos with Frank, Piper sees posters of Tristan's latest film Signed in Blood, where he played the main character Jack Steel. An embarrassed Piper wishes that her father hadn't taken on the Jack Steel franchise, which had became one of his popular roles.
Later that day he finds his daughter and her friends crying over the body of Jason Grace. He comforts his daughter and tells the others to call an ambulance.
The next day he lends Apollo and Meg his plane for it’s last trip so that they can take Jason’s body to the Bay Area while he, his daughter and the Hedges drive to Oklahoma.
Tristan cares about his daughter, Piper and he loved Aphrodite deeply although he was unaware that she was a goddess. He is very busy with his work, but tries to keep in contact with Piper as much as possible, even letting her help with his research for a movie role. He does not however believe in any kind of god or gods as if he did, he would always be looking for someone or something to blame for things. Even though he cares for his daughter, he is scared of making mistakes and will leave the tough choices to Jane, his assistant.
He is described as a handsome man of Cherokee descent with a perfect smile, dimpled chin, twinkly dark eyes, and closely cropped black hair. He has a sad look in his eyes, which he claims is because the Cherokee carry generations of pain and suffering with them. He has a fashionably scruffy beard, like he has not shaved in two days. When in the captivity of Enceladus, he is described as wearing torn slacks, with bare, mud-caked feet. While he was held hostage, his chest was scratched and his hands were handcuffed behind his back.
Tristan had a somewhat strained relationship with his daughter. Before he got into acting, the two would spend a lot of time together and talk about old Cherokee stories that Thomas McLean told them. When Tristan first got into acting, him and his daughter would joke about his role and the movie poster. When the movie became a big hit however, Tristan found that he had less time for Piper and did not understand why she kept stealing things (which she did to gain his attention). He eventually left most of his decisions up to his assistant, Jane. However, the two still get along as best they can and after the events of The Lost Hero, are trying much harder to make time for each other.
Thomas McLean is Tristan's father. Thomas told his son old Cherokee stories, which Tristan never believed or probably did not want to believe. While this left some distance between the father and son, even after Thomas died, Tristan could not sell his father's old house and most likely never will.
- One of Tristan's roles was in a James Bond film as a terrorist. Pierce Brosnan, who played Chiron in The Lightning Thief film, was also in a James Bond film, playing James Bond himself.
- The name Tristan can also mean "fame". This could be a reference to the fact that he is very famous. Yet the fact that Tristan also derives from the Latin word for "sadness" also demonstrates the sadness that he has had in his life and the sadness in his eyes (especially after getting kidnapped by Enceladus, before having his recent memories wiped by Piper).
- He is said to be an expert in surfing by Piper in The Lost Hero despite him growing up no where near water.
- He is one of the only living mortal parent of the seven who cannot see through the Mist .