A/N: This fic was inspired by this song, which I highly recommend listening to while reading this. Enjoy! :)

I don't own nothin'.

It was difficult to notice unless you knew him well, but every so often, a look would pass across Aang's face he carried the weight of the entire world.

Katara would catch it every once in a while. The first time she noticed it was when she visited the remains of the Southern Air Temple with him a few years after the end of the war. As she walked with him through the ruins, his face held an expression much older than his sixteen years.

His was an old soul; a soul that did not have the luxury of rest after seventy or eighty years of life. It was constantly reborn, destined to forever serve the world. She knew he loved helping others and keeping the world at peace, but there were times when she feared the responsibility and pressure might eventually take a toll on him.

When she mentioned her thoughts to him on their way back home, he smiled and told her not to worry–he'd technically done this job hundreds of times before. It was nothing he couldn't handle.

Katara smiled, kissed Aang's cheek, but didn't let her fears go.

The next time she saw it was the day Suki was killed by an attack from pirates. Sokka was nearly beside himself with grief. She had only been twenty-three, and she and Sokka had only been married three years. At the funeral, Aang gripped Katara's hand tightly, who was pregnant with Kya at the time. When she glanced at him, that same expression that had plagued him four years ago at the Southern Air Temple was written across his face once again. Grief over losing a close friend, and fear over disaster taking his wife, revealed just how old his soul really was.

After that day, Katara didn't see it for many years. The next several years were filled with joys of many kinds: the births of their own children, of friends', and a long period of peace in the world. It wasn't until Yakone began terrorizing Republic City that his true age resurfaced.

Aang came home from the trial that day exhausted, both physically and emotionally. He recounted the day's events with more than a little fear in his voice, despite the fact that Yakone was now behind bars and unable to hurt anyone else by bloodbending ever again. When he described the fear he saw in Sokka and Toph when they were attacked, he closed his eyes for several moments, and that was the moment Katara realized that, combined with his years in the iceberg and trying to keep the world at peace, the age of her husband's soul was starting to catch up with him, and he was beginning to age. Quickly.

They would have twenty-six more years together, years filled with joy and grief. The two would change in many ways, but the one constant throughout their years together was the love they shared. It was the one thing they could rely on to bond them together, for a simple kiss from one would lighten up the face of the other, and the years would melt away.

The final time Katara saw this expression, it was slightly different than all the others. It was in Aang's final moments of life, and she sat beside their bed, clutching her husband's hands, tears streaming down her face.

Aang murmured words of love and encouragement to her. Their family and friends surrounded them, tears brimming in their own eyes. As he drew his final breath, a kind of peace, combined with the experience of more years than anyone knew, settled across his face. And despite the pain and agony pressing against Katara's chest, being able to see her husband truly, finally, experience peace was a sort of solace in the midst of grief.

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