Hylas and Pirra are a profound Night and Day Duo. At the start of the series, they're as different as day and night. Hylas is a yellow-haired and tawny-eyed Outsider, while Pirra is a black-haired and dark-eyed daughter of Keftiu's High Priestess who gives herself a crescent scar on her cheek. Hylas grew up in the wilderness of Lykonia's mountains while having to take care of his little sister, the only family he remembers. Pirra spent the first twelve years of her life being confined in the House of the Goddess by her unloving mother while an Egyptian slave took care of her like a big brother. Hylas' tough life made him a self-reliant and practical survivor. Pirra in turn isn't initially well-suited to manage in wilderness, but she possesses more knowledge about different cultures and spiritual matters than Hylas. However, Pirra's fierce desire for the freedom Hylas' lifestyle represents to her makes her a wild child like him. At first they're together only out of necessity, but they gradually form a strong bond with each other and learn new things from one another throughout the series. You might say the entire series is about them learning to balance each other out, culminating in them becoming a mated pair at the end of the series.
Their animal companions Havoc and Echo reflect their learned co-operation as well. Havoc the lioness is from Thalakrea's volcano island, and she's the sacred creature of the Lady of Fire and Sekhmet, the lion-headed solar deity from Egypt. Echo the falcon is from Keftiu (a country that worships the Goddess and the Sea), and she's the sacred creature of Heru, the falcon-headed Egyptian god whose domain includes the Moon. Neither Havoc or Echo are solely fixed on the Sun or the Moon, though. Havoc's eyes are golden in daytime and silver in nighttime, and she considers nighttime to be the best hunting time. The Sun and the Moon aren't two separate things to her; she believes instead that "the Great Lion in the Up" is golden in daytime and silver in nighttime. As for Echo, the Sun and the Moon are both the domain of Heru (as Userref says in Eye of the Falcon), and Echo seems to have a role in the Sun's return at the end of Eye of the Falcon. Havoc is mainly paired with Hylas and Echo with Pirra, but both animals get along with their respective humans' significant one. Like Hylas and Pirra at first, Havoc and Echo can't stand each other until they learn to co-operate and share the duty of protecting their humans.
