I'm pretty sure Aaron Pierce did not show up in Season 1. I would have to go back and check, but I don't think we saw him at all. Besides Jack, I think Tony, Michelle and the first President Palmer were the only ones in all five seasons before this one. Since they killed all of them off, Jack is the only character in all six seasons, unless you count the pictures on Wayne's desk of his brother.
Sorry boyo, but Aaron Pierce was in Season 1, it's where we were introduced to him!! I remember because he's always played Secret Service type characters in movies, so it was no surprise to see him again as one!! Oh and for reference, since I wasn't sure about seasons 2-3!Aaron Pierce
I must be losing my mind...I haven't watched Season 1 in quite some time so I guess I just forgot about him.