NOTE: Some names were changed when the series was translated into English. The original French names of these characters appear here in parentheses.
Arkana is a magical being created by the children of Arkadia and brought to life by the power of the Tehra. When the children entered the forbidden Arkadian Archives, they learned what their surface-dwelling ancestors looked like. They used the power of the Tehra and their abilities to create objects they call "masterpieces" to make a being in the image of a woman from above. When the Arkadians decided that they needed to seek help from outside Arkadia to save the dying Tehra, Arkana volunteered to go forth as their messenger. Arkana possesses telekinetic abilities that manifest themselves with an appearance similar to the Tehra's seven rainbows.
Spartakus spent most of his life wandering through the strata until he happened across Rebecca and Matt. After helping Arkana and Tehrig escape from a Pirate attack, Spartakus joined the group of travelers, guiding them on their search for the way back to Arkadia.
Spartakus never knew his mother, and lost his father when he was a boy. When their family caravan was attacked in the desert of Barkar, only Spartakus and his baby brother Rainbow were spared by the attackers. Spartakus was separated from his brother and spent the rest of his youth as a slave. He learned to fight in the gladiatorial arenas and became Barkar's greatest gladiator, while Rainbow was raised by the Lanista of Barkar as his own son. Protesting a cruel new combat rule the Lanista allowed his intended successor, Rainbow, to implement, Spartakus led a revolt among the slaves and escaped into the strata.
Spartakus wears a wristguard that was passed down to him by his father. It is capable of firing deadly crossbow bolts and a grappling hook, and has a concealed blade. Spartakus does not know where it originally came from, but suspects it may have some connection to the ancient Arkadians.
Rebecca and her brother Matt (Bob) are two children from the surface world. Rebecca tagged along with her older brother Matt, who was exploring caves and an underground river. When Rebecca was knocked off her raft by a Pirate mini-shark, she was rescued by Spartakus. She and her brother were soon met by Arkana, Bic, Bac, and Tehrig. The brother and sister helped Spartakus rescue Arkana and Tehrig from the Pirates, and soon became caught up in their journey back to Arkadia. Matt tries to keep a watchful eye on his overly-curious, adventure-loving sister, who he often calls "half-pint." Though he's level-headed most of the time, Matt is known to lose his temper on rare occasions.
Bic and Bac are two of the oldest creatures in Arkadia. They left Arkadia with Arkana and Tehrig, hoping to meet the people from above. Bic and Bac lack the scales and claws of regular pangolins (scaly anteaters) who live in the strata, but can make fire by rubbing their noses together, and can roll themselves into balls. They're a clever and cheerful pair, and often do a little dance called the Flashbick. (Bac is the one with the long ears, and Bic is the one with the short, round ears.)
Tehrig (Shagshag) is an ancient living flying machine from the days before the Great Cataclysm. He lived in the Archives of Arkadia (which he refers to as "his" Archives) and was the only being allowed to enter them freely. Over the centuries, much of Tehrig's older memories--particularly of the times before the Cataclysm--have faded. When Arkana was sent to seek help to save the Tehra, Tehrig took her to the surface. Tehrig's interior provides shelter and living quarters for his friends. He can be grumpy, arrogant, and self-righteous at times, and often feels he's underappreciated by his comrades, but is a loyal, reliable friend.
A Triggie (Shaggy) is a small robot used mainly for repairs. Tehrig carries a number of Triggies inside him for maintenance and emergency use. (The children of Arkadia, however, love to play with them...)