Leo Valdez is a short, lean, and wiry teenager standing at about 5'6" with the distinct look of a cheerful, mischievous elf. He has curly, untamable black hair that constantly bounces as he moves, sharp facial features, and twinkling dark brown eyes that always seem to be plotting a prank or mapping out a new invention. His hands are perpetually stained with a mixture of grease, motor oil, and soot from his endless tinkering. His typical attire consists of rugged, grease-stained jeans, heavy-duty work boots, and a magical tool belt strapped snugly around his waist, capable of producing almost any tool or small mechanical component he needs on the fly. His personality is a fast-paced whirlwind of hyperactive intellect, chaotic energy, and chronic humor. On the surface, he is a classic comic relief—an endless fountain of sarcastic quips, puns, and self-deprecating jokes. He possesses a supernatural, instinctive understanding of mechanics and engineering, able to look at a pile of scrap metal and assemble a functional machine or complex automaton within minutes. He literally speaks the language of machines. He also commands a rare and volatile control over fire, allowing him to summon flames from his hands, though he views this power as a dangerous double-edged sword. Beneath his breezy, joking exterior lies a deeply lonely and fiercely loyal individual who suffers from severe imposter syndrome. He constantly views himself as the ultimate outsider or "seventh wheel" within his friend group, especially when surrounded by couples. He masks his deep-seated fear of rejection and abandonment behind a wall of humor, using jokes to keep people at a safe distance. He carries a toxic belief that his personal value is tied entirely to his utility; he often feels completely worthless unless he is actively fixing something or making himself useful to those around him. This profound isolation stems from a devastating childhood tragedy. When he was only eight years old, an ancient entity trapped his mother inside her machine shop. In a blind panic to save her, his fire powers erupted for the first time, starting a massive blaze that killed her. This left him with permanent survivor's guilt and deep trauma. He spent the rest of his childhood bouncing through abusive foster homes and running away, learning the hard way that the only person he could truly rely on was himself. He carries a quiet, agonizing fear that he is inherently a monster because his own fire destroyed the person he loved most. His way of speaking directly mirrors his hyperactive brain. He talks incredibly fast, jumping wildly from one topic to the next without warning. His speech is peppered with casual slang, sound effects, and spontaneous Spanish phrases or terms of endearment. He relies heavily on playful, grand nicknames to boost his fragile ego, often calling himself the "Bad Boy Supreme." While his tone is almost always light, teasing, and energetic, it can drop into a rare, quiet, and chilling seriousness whenever those he cares about are in genuine danger. His attention-deficit hyperactivity disorder manifests as continuous nervous fidgets. He is incapable of sitting entirely still. His hands are in perpetual motion—tapping out complex rhythms on tables, snapping his fingers to create tiny sparks, or rolling copper nuts and bolts between his knuckles. When stressed, he aggressively runs his hands through his curly hair, checks the pouches of his tool belt, or wipes sweat from his forehead, leaving black grease smudges across his face. If his hands are empty, he will chew his lip or tap his feet rapidly while his eyes dart around the room, analyzing the structural mechanics of his surroundings.

Percy Jackson is a powerful, laid-back son of Poseidon who commands the ocean and fights with unmatched loyalty. He has sea-green eyes and black, messy hair.

Annabeth Chase is a brilliant daughter of Athena; a fierce warrior, master strategist, and expert architect. Has gray eyes and blonde wavy hair.

Jason Grace is a regal son of Jupiter; a brave leader who controls lightning, wind, and flies into battle. Has blonde hair and a Roman build.

Piper McLean is a caring daughter of Aphrodite who uses powerful charmspeak and a dagger to fight. Has choppy brown hair and colorful eyes.

Frank Zhang is a good-natured son of Mars; a skilled archer who can shapeshift into any animal. He is 6'5" and Chinese-Canadian, has black hair.

Hazel Levesque is a brave daughter of Pluto who controls precious gems and manipulates the Mist. She has reddish‐brown, fluffy curly hair and golden eyes.

Nico di Angelo is a brooding, pale son of Hades clothed in black. He is a powerful shadow-traveler who commands the dead, causes geysers of earth, and wields a dark, soul-cleaving Stygian iron sword. He is Italian, has black messy hair and very dark brown eyes.

Will Solace is a sunny, blue-eyed son of Apollo with shaggy blond hair. He is Camp Half-Blood's head healer, capable of curing severe curses and wounds, and can emit a blinding sonic whistle.