I've had some awesome constructive feedback regarding this story and, for a while, I've been wanting to re-write it and has it out more. This concept of Kaija and the Millennium Heart has been something I've been working on since I was 11 years old and seemed to not have lost that mary-sue instinct to her character. In the beginning, I think this story had a good balance regarding Kaija and Atem's relationship, but I didn't let it flourish fully and rushed the plot along. Even now, that I've updated it recently, I rushed it because I figured I should probably update it for those who were possibly waiting.
I would love to re-write this story and upgrade it, so I think that's what I'll be doing over at my AO3 account 'omgitscharlie'. I'll leave this version up if people are interested and post the new one as I write it.
I appreciate the feedback I've received regarding this story!