After living seventy years without Zuko, Katara knew it was time for her to see him again. The rest of her family had already died. She had no one left except for her son who was doing a great job running the Fire Nation. He took on the position of Fire Lord on his sixteenth birthday as a present from Fire Lord Iroh. Katara knew she had done her job in the mortal world and she knew it was time for her to go to the Spirit World and see her friends again.
That night, Katara did die and take a long trip to the Spirit World.
Katara sat up and saw her friends. She saw a 16 year old Sokka hugging the fifteen year old Suki. She saw the twelve year old Aang and the twelve year old Toph embracing each other. All four of them stepped aside and allowed Katara to walk forward into the arms of the sixteen year old Zuko. She allowed herself to fall into Zuko's embrace and he kissed her.
The rest of Team Avatar joined in immediately and it created their first full group hug in seventy years.
Team Avatar was back together again