Beginning
"Katara…Katara, it's time for me to go…"
Aang's words were solemn in the silence, and yet not full of sorrow. In fact, they almost seemed to be intertwined in his familiar smile. Katara swiftly grabbed his hand in her's and brought it to her cheek.
"I'm sorry to have to leave you, sweetie."
At the old nickname, Katara smiled through the tears brimming in her eyes and gazed down to the love of her life. Aang's face, wrapped in wrinkles and laugh lines, wasn't sad or remorseful, but almost accepting of the inevitability of his fate.
The end of his life was near and his family and friends had already bid their farewells. Katara, however, knew that she had to be with him until the very end, as she had been with him since the very beginning.
As a solitary tear rolled down her cheek, Aang looked up at her and smiled once more and spoke quietly.
"Don't think of this as my end. This…this is only the beginning. I will be reborn in this world; I will live on."
"I know, Aang…"
"Promise me…" Aang's voice was very faint now as his breathing became shallow. "Promise me that whoever becomes the next Avatar…that you will be the one to train them during their waterbending training. Whoever it is will need your guidance."
Unable to speak due to the cascading tears down her cheeks, Katara simply nodded, clinging to her husband's hand.
As if a switch had been flipped, Katara could almost sense as Aang hung on the precipice of life and death. Inhaling one last time, Aang gazed up into the beautiful eyes of his beloved and whispered, "I will always love you, Katara."
Then, his eyes closed on the world and he let himself go.
As Katara sobbed over her husband's lifeless body, thousands of miles away, a young baby girl opened her blue eyes and wailed as air filled her lungs. She was placed into her mother's arms and the woman caressed the babe gently.
"Hello, Korra. Welcome to the world."