Who to blame...

For the War:
Sozin for starting it
The Comet for existing
Aang for dying

For Zuko Going Bad:
Zuko for being stupid
Aang for not coming later
Azula for influincing Zuko
Fire Lord Ozai for Banishing Zuko

For Aang Running Away:

The other monks at the air temple for sending him away
The other Monks for telling him he was the Avatar too early
The other kids for excluding him
Aang for running away
Gyatso for not talking to Aang 5 seconds earlier

I'm starting to sound like the Bush administration