User blog comment:FTWinchester/Season 9 Recurring Characters/@comment-3481504-20130718163128/@comment-3045936-20130721001543

The only realistic reason for having Gabriel return, but it's in three parts that add into one. 1. Out of all the Archangel and kind of angels if you count, how royal to a fault Cass was to his plans in season 6 and 8 to kill Raphael and seal angels in Heaven. Gabriel was acting to protect humans, even though he killed while being a trickster. 2. As part of the first reason, he would be the only killed angel that wasn't there to be hit by Metatron's spell that I think God would directly bring back to life, (This is the method, and the first part is more of why.) 3. Final outcome, if Gabriel would be reived here is a question, what happens after they end Metatron's spell? Like, minus maybe Crowley all the big bads are either sealed away, or killed.

So, logically it stands that minus bring in another one, Gabriel being alive doesn't bring ruin to the Earth. Like how Michael and Lucifer fight would, or how Raphael greatly wanted for it to happen, and went into a civil war to make it happen. Gabriel wouldn't do either bring ruin to the Earth or work plans to bring what does destroy the Earth, so Gabriel wouldn't turn out to be a big bad. Unless of course he started acting like how Godstiel did in season 7,  acting like a god and telling the world what to do. My theory.