Evanna was a special Tempest Guardian - she could communicate with creatures more so than anyone else during her training. When she was able - she left Saphina to explore the realms of Aultora in search of creatures and beasts that were known only in legend.
She stumbled upon a Bluebell serpent on her travels whose tail had been cut off and left for dead on the side of the road. The Bluebell serpent is a creature that has a tipped tail like a bell, that it would ring to communicate with other Bluebells. It was known for merchants to cut off the tail and sell for gold.
Evanna rescued the Bluebell serpent and named him Azra, once his tail was healed and strong enough to move around on - she attached a small golden bell to the end to resemble the one he lost.
After that, they were inseparable, little did Ina know that Azra was no normal Serpent, but in fact, a Voma (Naga Race) that can take the form of a simple serpent.
He became her familiar, vowed to protect her for saving his life.