[ShadowHeart]

Those pics of each character that were made when the game first came out have nothing to do with actual scenes in the game or the story. They are just meant to show the characters.. Barret never goes to the church in sector 5 with Marlene, you never see Vincent sitting on a roof top with lightning in the background sky, and so on.. Maybe they chose to have Aeris with the Highwind because in the game she says she always wanted to see it/ride it/whatever.