Worst thing Azula and Zuko did?

Azula - taking down the Kyoshi warriors
Zuko - betraying his uncle in Ba Sing Se

Azula tormented zuko as a kid and didnt even bat an eyelash when she told zuko their mother was gone hoặc that their grandfather died.

Zuko- Turning on his Uncle
Azula- becoming FireLord (that was bad for her and everyone she banished she just went mental)

Azula- tried to kill Zuko
Zuko- Turned his back on Uncle