Where is Zack's personality developed? I've not seen a lot of him in the original game, so I just figured he'd be fleshed out in Crisis Core or Last Order.

What did Last Order change about the canon? I know Cody didn't like it, but he said I should watch it and see for myself after I finished playing, and didn't tell me what was different (of course, he said this when I hadn't yet gotten to certain spoilerific parts of the game that Last Order would've totally ruined for me).