Disclaiming Banner: Let it be known that ATLA belongs to Mike & Bryan. Not to some piddly fic writer.
Exacerbate
When Katara decided to forgive Zuko, it wasn't for any altruistic reason. She had decided to forgive him because she had had a taste of vengeance. And she didn't like it.
That monster, that had pretended to be a solider when he killed her mother would have been easy to snuff out. He had been empty and worthless. No one would have missed him.
She had taunted the fire-bender with his past mistakes. But Katara understood now how easy it was to grasp at something she'd wanted for so long.