like ringo's turner said, it's a battle of ideologies. Ringo in one hand wants practically no one hurt, so SF goes and hunt down all "possible" people who are candidates for being the sky king or in essence those who can fly. Also they hunt down those who influence those the rest of the community and inspire them to fly. Thus, Simca, and the other kings in genesis. So SF thoughts are, prevent people from flying so they don't hurt themselves when they fall. As for why she has so many thoughts inside, it's because she loves ikki and she wants him to understand her. That's the hole point in their fight. She wants ikki to understand that she's trying to protect him, while he's saying that everyone is different and that everyone can fly if you let them.Try as I might, I still can't see Ringo other than, in the best view possible, as a confused or lead astray ATer. I won't go as far as saying she is evil, but I can confidently say she is not good or innocent, and that her actions, whatever reason she gives them, are bad (at least by what I understand these definitions to be). She seems to be under the premise that the means justifies the ends, but this premise is only good, to me that is, when we know for sure the ends; and even then it's still questionable. I base all this on the way she has been developed in the story--her overt actions, her internal dialogs, her internal struggles (questionings), and her stated desires and beliefs.
not sure where you're going with this....To me, if she is not confused nor lead astray, then she is a hypocrite and bad in the sense that, if I were Ikki, I would not want to have her as a friend or family. Place yourself in Ikki's shoes and imagine your sister (not parent, but an equal), or a very close friend, do all the things Ringo has done; then decide how you feel--you may be surprised, or I may be.
again, as i was saying it all depends on what you believe. It's not like she's doing it for fun or pleasure and in fact quite the opposite. Also stating that you identify yourself with the protagonist can be flawed too. What if the main character is wrong?It is important you identify with the main character, Ikki, and not with Ringo. Don't see yourself as Ringo (though she may be a favorite character) doing these "things", justifying them the way she does; see yourself as having these "things" done to you by some outside force.
Also, just to state, how do you determine who is good, who is bad, who's the bad guy, who's the good guy? It's all about what you believe and the means of how your going to do it. For example, (hopefully you've played this) let's talk about Kingdom Hearts. (also i didnt wanna bring in religion) Sora, the main character wanted to save Kairi. Riku (his best friend) also wanted to save kairi. Sora tries to save her in the means of fighting the heartless and searching for her heart that way. As for riku, he joined the heartless and tried to find her heart in that means. They both took opposite sides, but does that mean that one of them is right and one of them is wrong? No, they both are striving for the same goal. So what i'm trying to say is, you can't say one person is bad/evil for believing one thing or joining one side, while another person is good for believing a certain way or joining the other side. Both are right, but they both just found a different means of being "right," even if they do have conflict with one another. ....not sure if that's the best analogy but, hopefully u get what i mean.