system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar: The Last Airbender] Why does the Fire Nation bother with eliminating the Avatar?

The Fire Lord was able to kill the Avatar before Aang, but the Avatar just gets reborn when the last incarnation dies. The Fire Lord has to know about this, so why bother with it? Why not instead just try to conceal him in a cave or imprison him?
gpt
Avatar Roku was not killed by Fire Lord Sozin and he most certainly was not killed by Fire Lord Ozai, who wasn't born for decades afterwards.

And that is exactly what he wants to do at the start. As time goes on it becomes increasingly clear that Aang is becoming very close to fully realizing his role as The Avatar, and he wouldn't be able to be imprisoned for long and it would just be easier to kill him and imprison the next Avatar before they could become a credible threat.

Or he is trying to speed along the cycle for the next Avatar to be born in the Fire Nation, so they can indoctrinate them for their cause. Not necessarily possible, but it probably at least crossed his mind.