I read that you can possibly restore the Blades, But I was just wondering, Do I have to kill Parrthy or can I leave him, and still restore the Blades

You can restore the blades first with recruits. Then ignore their "kill Paarthurnax" ultimatum.

You must kill Paarthurnax.

Strike it down with justice and feel the glory. Then post a picture to mock all lovers of "Paarthy".

[img]http://img560.imageshack.us/img560/9833/deathofpaarthurnax.jpg[/img]