Max was born a drakomas, but the Arel heritage from his father made him more compassionate than others of his kind. He nested as many of his brothers as he could find, and he taught them all the Bane-Cry. Answering his brother Illarion's Bane-Cry led to their transformation into some of the first Were-Hunters. The god Dagon, upon the wishes of King Lycaon, merged them with his sons to become Katagari dragons. After one of the sons accidentally murdered another, he blamed the death on Max and Illarion. Max took the brunt of the punishment to protect his brother. That is how Max became the Dragonbane.
A couple millennia later, Max answered the Bane-Cry of his brother Hadyn in ancient Greece. He was unable to save Hadyn's life, but he met his mate Seraphina while he was mourning. He lived with her tribe for three years until their mistreatment of him drove him away. Unbeknownst to him, Seraphina was pregnant at the time. Because she couldn't reach him, she raised their dragonets Hadyn and Edena on their own. He didn't see Seraphina again until she tracked him down in 2015 for help rescuing their children from Kessar. They reconciled and are happy together for the first time.
Maxis and his dragonets are all immune to gallu bites.
In Dragonsworn, Falcyn notices that Max and Shadow look very similar in profile. We know that Max's father is an Arel but not his name. Max and Shadow could be brothers.