Thoros of Myr is the priest. Beric Dondarrion is the guy who was resurrected. IIRC, he was the one sent by Ned Stark to bring the Mountain to justice for attacking villages in the Riverlands.
Exactly.
But if I remember right,
Jamie put a dagger in to somebody's eye when capturing Ned (after the guard speared his thigh), and I think that was Beric, who wore an eye patch when fighting the Hound. Or just coincidence that Beric had the same wound, I'm forgetting this timeline now.
Either way, Beric was tasked by Ned to go get the Mountain, and somewhere along the way joined the Brotherhood without Banners and converted to the Lord of Light religon. I also noticed his flaming sword was legit (fueled by his blood), whereas Stannis' flaming sword was a fugazi.