Well, when I hear discussions about fans booing Brett, I think back on Aaron's first year as the starter. Fans booed him when he first went out into the field; they wanted Brett back and they felt Rodgers was instrumental in him leaving.
Now, Aaron is our new hero.
I admit I was disappointed when Brett retired, came back as a Jet, retired, and then came back as a V. Betrayed, absolutely. Hated him, no. It's a rare player than sticks to one team their entire career.
I think the fans this fall will cheer him for the player he was. He will always be remembered as a Packer, though some people in MN still think of him as a V.
Holding a grudge against Brett is pointless. Brett has no idea who you are, and probably doesn't even care about your unproductive feelings.