Personally I love Annie!
SamBurke, I think your friend is somewhat right. Many of the characters don’t really develop; many of them also don’t get much screen time except for in battles, when development really isn’t prime. Don’t quote me on this as I’ve just started the manga, so I’m just going by the show, but here’s how I see it…
- Mikasa definitely develops. I wasn’t a fan of her at first because I just saw her as a protector of Eren, but she is so much more than that. She’s a protector of what Eren stands for — freedom from the Titan tyranny, and perhaps all tyranny — and this really shows when she saves all of the villagers from the titans by threatening the political dude who is plugging the gate with his grain supply. She is out of her culture in this place, the last of her kind so to speak, and has found a home with Eren. To her, he is everything because he is literally all she has — he is all she has to remember her old life with, and she owes him everything for saving her. So her loyalty to him makes sense; it isn’t brazen or ignorant or unnatural. And she has developed. Initially, she wouldn’t let Eren do things his way; now, she understands that sometimes he needs to do things dangerously and that he is willing to risk his life to save the world. So I’d say she’s grown.
- Armin also develops. Initially, he is under-confident when sharing his beliefs; however, he gradually becomes much more confident throughout the anime. As he becomes more recognized for his intelligence, his personal growth expands: he is able to do things he may never have imagined like catching Annie (incredibly dangerous). He could not have done this at the underconfident level he was at the beginning of the anime.
- Jean has probably developed more than anyone else. Initially I hated him. He was an assinine, weak jerk with nothing to stand on. He was a flat character. A bully. However, when he began talking (fighting) more with Eren, he changed. He joined the Survey Corps, for goodness’ sakes. And his relationship with Marco, who told him he was a good leader, is a prime example of character development. This was the reason for much of Jean’s development after the fact. He does what he does for Marco, the only friend he had; the only person who believed in him. He refuses to let Marco down. If this isn’t character development from the piece of crap Jean was in the beginning, I don’t know what is.