Moosha is a fully mature DaRooga. Most Timallan ride DaRooga even though they are renowned for their impossibly willful characters. But Timallan pair their novice healers with their DaRoogas almost at birth, and the connection they develop is incredibly deep.
Once you have that bond there isn’t a creature with more strength, endurance or fierce loyalty that you could hope for. Moosha would defend TiaMuati to the death. For her part TiaMuati has a stronger connection with Moosha than with any other creature on earth. They are a formidable team.