Pax is of the first generation of children born with no color designation under the new Solar Republic.
Pax was born in secret on Virginia’s flagship, the Dejah Thoris, shortly after the start of the Rising. During this time his father, Darrow, was widely believed to be dead. For the first year of his life, until the formation of the Solar Republic, Pax remained in the Asteroid Belt under the protection of Niobe au Telemanus. His existence was made public shortly after his mother’s ascension as Sovereign.
Darrow's Triumph was on the Ides of Mars (15th of March), which means Pax was conceived a few days before this date, making his birthday somewhere in December.
When Darrow held him for the first time, he put his ear to listen to Pax's heart. He told Virginia that he can hear the heartbeat of his people through his son's heart.
Daxo au Telemanus taught him how to make sandcastles in South Pacifica, Earth. He cried when the waves destroyed his castle, but Daxo told him that is life and he just needs a short memory for the bad things and long one for the good moments.
He stated that Kavax is his co-godfather, because he and Sevro arm-wrestled for the title and there was a lot of cheating involved.
In Iron Gold, Darrow observes that Pax is half his height. He has straw blond hair and rose-gold eyes. In Dark Age, Pax tells Sefi 'So I look upon you with my father's eyes to ask: what do your old ways say of honor?' Darrow's eyes color is never mentioned, but this alludes that Pax has his father's eye color. He smiles like his mother and broods like his father. He is a tad smaller than Electra.
He has no sigils and he is the first child in 800 years to not have them implanted. According to Lyria, his head is as sigilless as Darrow's.
Also, both Ephraim and Lyria note the similarities between Pax and Darrow, going as far as to think for a few seconds that Pax was actually Darrow, until they realize that he is actually a child.
In Dark Age , he wears the crests of his parents - the lion and the pegasus - on the shoulders of his jacket. He is as tall as Kieran of Lykos, his uncle, and has scars and deep circles under his eyes.
In Dark Age, Pax defeated three Obsidian trainees on his own violently and mercilessly, all the while looking bored. Ephraim notes that he has his eyes closed, which, combined with Pax's interest in meditation lessons with Ozgard, can suggest that he has the ability to control his mind in ways average human can't. He is not as fast as Electra, but he is notably crueler. He refused to play by Obsidian rules and, much like his father, changed the paradigm to suit himself. He broke an opponent's kneecap, another's skull and embedded a piece of the bone stave into the neck of the last, 2 millimeters away from his carotid artery. Ephraim notes that it all looked like a dance, like something Pax saw before happening and now must go through the motion to entertain the Obsidians.
He has a great memory, as he can draw a very detailed map of the city of Olympia from memory alone. He can also reproduce conversations word by word as he heard them. He has access to secrets of state like: Ascomanni, the Figment parasite, Occulus, the city-planet from the Asteroid Belt, Trigg ti Nakamura's past and so, he uses his knowledge to help the Republic.
He is a very skilled pilot, admiring the likes of Rex and Char (although he prefer Rex, considering her a ballerina) for most of his childhood. He managed to bring down a torchShip, coordinating his allies impeccably, so that he had a clear passage to deliver the fatal blow.
He is fluent in Nagal, the Obsidian language and he is very knowledgeable about their customs and habits. He also uses his senses to his advantage, as he could deduce Valdir's relationship with Freihild by observing them.
Pax is also a very skilled mechanic, as he built from scraps a hoverBike that impressed his father. He also managed to make a pair of strong harnesses which helped him and Electra escape Olympia with Ephraim ti Horn, so that Sefi couldn't use them as hostages.
It can be inferred from the way Pax defeated the three Obsidians that he may possess the ability to use the Mind's Eye. Should this be true, it would mean he would have the capabilities to become one of the best Razor masters in the Solar System.