Who is Mavo from Peace Child and what is their importance?

Mavo works as a houseboy for the Richardson family. He even travels to Kaybuga with the family for the birth of their second son. On the return trip, the entire party capsizes into the crocodile-infested river. Mavo climbs onto the overturned canoe and aids in spotting the body of Stephen, the Richardson's toddler-aged son, in the muddy water.