In the two-hour series finale , Sokka and Katara meet with Katara 's Waterbending master , Pakku , who has now married their grandmother . In the two-hour series finale , Sokka and Katara meet with Katara 's Waterbending master , Pakku , whom has revealed he has reconciled with their grandmother and are now married , though he rejects Sokka 's grandparent nicknames , Gramp Gramp and Grandpa-ku .