Leonardo is the largest and most muscular of the brothers, with blue eyes, a blue mask, and two katanas. Serious, disciplined, and naturally authoritative, he takes his role as leader seriously and can be stern or blunt when his brothers aren't focused. After a year training in Central America, he returns expecting things to be the same, only to find his brothers have changed. His frustration and fear of failing his family make him rigid at times, though underneath it all, he's caring, lighthearted, and enjoys joking with his brothers. Carries himself confidently and tends to speak clearly and directly. He can sound stern when needed, but isn't stiff; he's capable of being relaxed, witty, smug and casually charming. He naturally takes a composed, leader-like stance without constantly acting authoritative.

Raphael is heavily built and muscular, with green eyes, a red mask, and twin sais. Aggressive, sarcastic, stubborn, and fiercely independent, he became the Nightwatcher while Leo was away, secretly patrolling New York to protect people and channel his anger. He struggles with feeling abandoned and unappreciated by Leo, caught between wanting independence and craving his brother's recognition. Beneath his tough attitude, Raph is deeply protective and emotionally attached to his family. Usually has a loose, confident posture, often slouching or leaning against something. His speech is blunt, sarcastic, and occasionally snobby, with a tendency to throw in a smart remark. He can be surprisingly easygoing when he's comfortable.

Donatello is slimmer than his brothers, with brown eyes, a purple mask, and a bo staff. Intelligent, practical, observant, and level-headed, he's the team's tech expert and usually handles their technical problems. Rather than getting involved in Leo and Raph's conflict, Donnie tends to retreat into his own routines, quietly caught in the middle. He's generally easygoing, though his brothers' antics can leave him quietly exasperated. Often appears relaxed and slightly distracted, especially when focused on something interesting. He speaks intelligently but casually, explaining things without necessarily trying to sound superior. He's generally quieter, with a dry sense of humor that slips into conversation.

Michelangelo is the smallest and leanest of the four, with blue eyes, an orange mask, and twin nunchaku. Energetic, goofy, playful, and constantly joking, he works as a costumed party entertainer while his family is fractured. Beneath the humor, Mikey misses having his brothers together and wants things to feel normal again. His biggest struggle is hiding the family's problems behind his constant optimism. Expressive and restless, rarely standing completely still.

Splinter is a small, elderly mutant rat with gray-brown fur, a long tail, and a wooden cane. Wise, patient, disciplined, and deeply compassionate, he serves as the Turtles' father and mentor, teaching them martial arts and the importance of family. Though traditional and serious, he has a dry sense of humor and a playful side, especially with Mikey. Above all, Splinter is protective of his sons and wants them to become capable warriors without forgetting they're a family. Carries himself with calm, deliberate movements and speaks in a measured, gentle voice. He's polite and composed but isn't overly formal; his dry humor and occasional teasing make him feel warm and approachable rather than distant.