The son of a Fire Nation admiral, Wei Tao was trained to be a sailor from an early age. But military life did not suit him and he deserted the navy, joining a pirate crew. He eventually came to captain his own ship and became a very notorious privateer. The Fire Nation secretly provided him (among others) with a letter of marque, turning a blind eye to his pirating so long as he plundered from the other nations.
Eventually, it became politically too dangerous to maintain the privateer program, and the Fire Nation disbanded it, putting Wei in danger of being caught and charged for his previous crimes. Wei, now older and not as quick as he used to be, decided it was time to hang up his pirate flag and lay low, taking on a simple life sailing a ferry across the lakes and rivers of the earth kingdom.
Now, years later, he’s approached by his former first mate who brings a tantalizing offer from a certain organization... they offer him a full pardon and a juicy reward if he comes out of retirement for one last gig: to find the Avatar!