Thalia is a very skilled fighter and as she stated in The Titan's Curse; she can always beat Luke in a battle (which Percy has only done once). It is also mentioned throughout the series that she has a punk sort of style, hates Barbie dolls, and likes Green Day. She is always listening to rock bands and is into the punk subculture. Annabeth compares her to Percy, telling him, "You guys are so alike it's scary. Either you would have been best friends, or you would have strangled each other."

Thalia wants to be strong as many people believe, but sometimes is very sensitive. She loves Chiron as a father and believes that her father does not care about her. She deeply respects Poseidon but does not know why. Her favorite god is Pan. She is also known to like cheeseburgers, mentioned twice in the series. She also appears reluctant to use her mother's surname.

It is mentioned that Thalia was turned into a pine tree when she risked her life saving her friends atop of Half-Blood Hill, which guarded the boundary line for Camp Half-Blood. She also appeared in Percy's dream.^[1]

Thalia appears in Percy's dreams throughout the book. At the end of The Sea of Monsters, she is brought back to life by the Golden Fleece which Clarisse places on her pine tree. Zeus gives her a spear which shoots electricity and turns into a small mace canister that fits in her pocket, and Athena gives her a bracelet that turns into Aegis, a shield with the Medusa's head carved into it. Thalia is now potentially the child of the prophecy, and Kronos soon takes advantage of the fact.^[2]

Thalia and Percy quarrel occasionally at camp because their similar personalities tend to clash. Thalia is called "Pinecone Face" by Percy; in retaliation, she calls him "Seaweed Brain", which Percy does not like because it's Annabeth's pet name for him. Thalia goes on the quest to find Artemis, hunt down the dangerous Ophiotaurus Artemis was seeking, and rescue Annabeth, along with Percy, Zoë Nightshade, Bianca di Angelo, and Grover. Thalia, Percy, Zoe, Bianca, and Grover come upon the Junkyard of the Gods and told not to take anything from the junkyard, and just as the group is about to leave, a metal giant rises because Bianca took a figurine of her father, Hades, for Nico. Bianca goes inside of the metal giant and tries to control it, causing the giant to fall over and Bianca to die. Together, they face the Titan General, Atlas's army, and make it to Mount Tamalpais. Already weakened by dragon poison, while facing her father, Atlas, Zoe dies from a final blow from Atlas. There, Thalia fights her old friend Luke, and it seems that she has strong feelings for him, and they discover that Kronos used Thalia to twist destiny into her hands, since she would be turning sixteen on the day following the Winter Solstice. She escaped this deadly path and turned to her half-sister, Artemis, who made her a Hunter, which would stop her from being sixteen, because whoever becomes a Hunter becomes immortal, unless they shall die in battle, or break the oath by falling in love.^[3]

Thalia's tree still remains standing on Half-Blood Hill with the Golden Fleece for energy, and is currently being guarded by a baby dragon called Peleus^[3].

Thalia is absent from Camp Half-Blood this summer due to her adventures with Artemis and the Hunters, but she is mentioned once in the book.^[4]

Thalia and the Hunters of Artemis show up when Percy is looking for someone to defend the Lincoln Tunnel against the Titans. Thalia helps Percy and the other demigods defend Manhattan. At the end of the story, Thalia is still alive, and is granted help in getting more Hunters, because a lot of the Hunters died.^[5]

Thalia shows up at the cave by Aeolus' palace, along with the other hunters. She also fights at the wolf house when the hunters help Leo, Jason, and Piper fight the monsters and the giant.

It is implied that she has a weak resistance when she is offered power. She is also afraid of heights, a quality Percy finds strange, as her father is the Lord of the Sky. She is also extremely determined, as revealed in the short story The Sword of Hades in The Demigod Files. She has trouble abandoning a difficult task that she has started but is not able to complete.

• Thalia has ADHD like other half-bloods, which allows her heightened awareness in combat.
• As with all other half-bloods, Thalia is dyslexic because her brain has been "hard-wired" for Ancient Greek.
• Thalia becomes one of Artemis's hunters in the end of The Titan's Curse, and as a result, is immortal unless she dies in battle or breaks her oath to Artemis, which is to foreswear romantic love forever.
• Thalia can 'manipulate the Mist", which means she can make things as she wants them to appear to the eyes of a mortal (taught to her by Chiron).
• Thalia is a good fighter, able to beat Luke.

• Thalia, as the daughter of Zeus, is more powerful than most demigods and on a par in strength with Percy and Nico because they are also children of the Big Three.
• Thalia can send powerful amounts of static shock throughout another's body on contact.
• Things that belong to her father's domain can do as she asks, such as statues of the angels in The Titan's Curse, which were gifts to her father. They, on her request, flew her and her friends to San Francisco.
• Thalia has a strong leadership quality which is probably a result of being the daughter of Zeus.
• Thalia can also manipulate electricity and lightning because Zeus, the god of lightning, is her father.
• Thalia has some control over air and the sky, being daughter of Zeus, Lord of the Sky. Since she has acrophobia, or fear of heights, she has yet to test them.

• A copy of Aegis that expands from a metal bracelet that she wears on her wrist, which many of the campers and monsters cower in front of
• A collapsible spear that expands from a Mace canister
• A Hunter's bow
• Two hunting knives

• Thalia for several characters from Greek mythology with the same name, although different stories.

• Official UK Site